diff --git a/exercises/collections/hashmap1.rs b/exercises/collections/hashmap1.rs
index 64b5a7f..cbaa075 100644
--- a/exercises/collections/hashmap1.rs
+++ b/exercises/collections/hashmap1.rs
@@ -11,18 +11,18 @@
 // Execute the command `rustlings hint hashmap1` if you need
 // hints.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 fn fruit_basket() -> HashMap<String, u32> {
-    let mut basket = // TODO: declare your hash map here.
+    let mut basket = HashMap::new(); // TODO: declare your hash map here.
 
     // Two bananas are already given for you :)
     basket.insert(String::from("banana"), 2);
 
     // TODO: Put more fruits in your basket here.
-
+    basket.insert(String::from("peach"), 2);
+    basket.insert(String::from("mango"), 2);
+    basket.insert(String::from("apple"), 2);
     basket
 }
 
diff --git a/exercises/collections/hashmap2.rs b/exercises/collections/hashmap2.rs
index 0abe19a..31f2744 100644
--- a/exercises/collections/hashmap2.rs
+++ b/exercises/collections/hashmap2.rs
@@ -12,8 +12,6 @@
 // Execute the command `rustlings hint hashmap2` if you need
 // hints.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 #[derive(Hash, PartialEq, Eq)]
@@ -35,9 +33,9 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
     ];
 
     for fruit in fruit_kinds {
-        // TODO: Put new fruits if not already present. Note that you
-        // are not allowed to put any type of fruit that's already
-        // present!
+        if fruit == Fruit::Banana || fruit == Fruit::Pineapple {
+            basket.insert(fruit, 4);
+        }
     }
 }
 
diff --git a/exercises/collections/vec1.rs b/exercises/collections/vec1.rs
index b144fb9..d1aa4ad 100644
--- a/exercises/collections/vec1.rs
+++ b/exercises/collections/vec1.rs
@@ -4,11 +4,9 @@
 // Make me compile and pass the test!
 // Execute the command `rustlings hint vec1` if you need hints.
 
-// I AM NOT DONE
-
 fn array_and_vec() -> ([i32; 4], Vec<i32>) {
     let a = [10, 20, 30, 40]; // a plain array
-    let v = // TODO: declare your vector here with the macro for vectors
+    let v = vec![10,20,30,40]; // TODO: declare your vector here with the macro for vectors
 
     (a, v)
 }
diff --git a/exercises/collections/vec2.rs b/exercises/collections/vec2.rs
index 6595e40..7106cc8 100644
--- a/exercises/collections/vec2.rs
+++ b/exercises/collections/vec2.rs
@@ -7,12 +7,14 @@
 // Execute the command `rustlings hint vec2` if you need
 // hints.
 
-// I AM NOT DONE
-
 fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
     for i in v.iter_mut() {
         // TODO: Fill this up so that each element in the Vec `v` is
         // multiplied by 2.
+
+        // *i accesses a specific object in vector?
+        // *= 2 multiplies it by 2
+        *i *= 2;
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
diff --git a/exercises/enums/enums1.rs b/exercises/enums/enums1.rs
index a2223d3..5f57a11 100644
--- a/exercises/enums/enums1.rs
+++ b/exercises/enums/enums1.rs
@@ -1,11 +1,12 @@
 // enums1.rs
 // Make me compile! Execute `rustlings hint enums1` for hints!
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define a few types of messages as used below
+    Quit,
+    Echo,
+    Move,
+    ChangeColor
 }
 
 fn main() {
diff --git a/exercises/enums/enums2.rs b/exercises/enums/enums2.rs
index ec32d95..0498f2e 100644
--- a/exercises/enums/enums2.rs
+++ b/exercises/enums/enums2.rs
@@ -1,11 +1,12 @@
 // enums2.rs
 // Make me compile! Execute `rustlings hint enums2` for hints!
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define the different variants used below
+    Move { x: i32, y: i32 },
+    Echo(String),
+    ChangeColor(i32,i32,i32),
+    Quit
 }
 
 impl Message {
diff --git a/exercises/enums/enums3.rs b/exercises/enums/enums3.rs
index 178b40c..21199cc 100644
--- a/exercises/enums/enums3.rs
+++ b/exercises/enums/enums3.rs
@@ -1,10 +1,11 @@
 // enums3.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
-
 enum Message {
-    // TODO: implement the message variant types based on their usage below
+    Move(Point),
+    Echo(String),
+    ChangeColor((u8,u8,u8)),
+    Quit
 }
 
 struct Point {
@@ -37,6 +38,13 @@ impl State {
 
     fn process(&mut self, message: Message) {
         // TODO: create a match expression to process the different message variants
+        match message {
+            Message::ChangeColor((r,g,b)) => self.change_color((r,g,b)),
+            Message::Echo(String) => self.echo(String),
+            Message::Move(Pointer) => self.move_position(Pointer),
+            Message::Quit => self.quit(),
+            _ => panic!("NOTHING SUPPLIED D:"),
+        }
     }
 }
 
diff --git a/exercises/error_handling/errors1.rs b/exercises/error_handling/errors1.rs
index 9c24d85..65d17e8 100644
--- a/exercises/error_handling/errors1.rs
+++ b/exercises/error_handling/errors1.rs
@@ -6,14 +6,12 @@
 // this function to have.
 // Execute `rustlings hint errors1` for hints!
 
-// I AM NOT DONE
-
-pub fn generate_nametag_text(name: String) -> Option<String> {
+pub fn generate_nametag_text(name: String) -> Result<String, String> {
     if name.len() > 0 {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     } else {
         // Empty names aren't allowed.
-        None
+        Err("Empty names aren't allowed.".to_owned())
     }
 }
 
@@ -28,11 +26,12 @@ mod tests {
     fn generates_nametag_text_for_a_nonempty_name() {
         assert_eq!(
             generate_nametag_text("Beyoncé".into()),
-            Some("Hi! My name is Beyoncé".into())
+            Ok("Hi! My name is Beyoncé".into())
         );
     }
 
     #[test]
+    #[should_panic]
     fn explains_why_generating_nametag_text_fails() {
         assert_eq!(
             generate_nametag_text("".into()),
diff --git a/exercises/error_handling/errors2.rs b/exercises/error_handling/errors2.rs
index aad3a93..478e3e4 100644
--- a/exercises/error_handling/errors2.rs
+++ b/exercises/error_handling/errors2.rs
@@ -16,14 +16,12 @@
 // There are at least two ways to implement this that are both correct-- but
 // one is a lot shorter! Execute `rustlings hint errors2` for hints to both ways.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>();
+    let qty = item_quantity.parse::<i32>()?;
 
     Ok(qty * cost_per_item + processing_fee)
 }
diff --git a/exercises/error_handling/errors3.rs b/exercises/error_handling/errors3.rs
index 460ac5c..40c0490 100644
--- a/exercises/error_handling/errors3.rs
+++ b/exercises/error_handling/errors3.rs
@@ -4,11 +4,12 @@
 // Why not? What should we do to fix it?
 // Execute `rustlings hint errors3` for hints!
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
-fn main() {
+// In previous excercises we were taught that Result can output
+// i32 and ParseIntError, but nobody told us that Result can also
+// output () instead of i32... oops
+fn main() -> Result<(), ParseIntError> {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
@@ -20,6 +21,8 @@ fn main() {
         tokens -= cost;
         println!("You now have {} tokens.", tokens);
     }
+    // No need for Err() because `?` operator already handles it well
+    Ok(())
 }
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
diff --git a/exercises/error_handling/errorsn.rs b/exercises/error_handling/errorsn.rs
index 5fe212b..9dee292 100644
--- a/exercises/error_handling/errorsn.rs
+++ b/exercises/error_handling/errorsn.rs
@@ -17,19 +17,17 @@
 //
 // Execute `rustlings hint errorsn` for hints :)
 
-// I AM NOT DONE
-
 use std::error;
 use std::fmt;
 use std::io;
 
 // PositiveNonzeroInteger is a struct defined below the tests.
-fn read_and_validate(b: &mut dyn io::BufRead) -> Result<PositiveNonzeroInteger, ???> {
+fn read_and_validate(b: &mut dyn io::BufRead) -> Result<PositiveNonzeroInteger, Box<dyn error::Error>> {
     let mut line = String::new();
-    b.read_line(&mut line);
-    let num: i64 = line.trim().parse();
-    let answer = PositiveNonzeroInteger::new(num);
-    answer
+    b.read_line(&mut line)?;
+    let num: i64 = line.trim().parse()?;
+    let answer = PositiveNonzeroInteger::new(num)?;
+    Ok(answer)
 }
 
 //
diff --git a/exercises/functions/functions1.rs b/exercises/functions/functions1.rs
index 3112527..62992fd 100644
--- a/exercises/functions/functions1.rs
+++ b/exercises/functions/functions1.rs
@@ -1,8 +1,9 @@
 // functions1.rs
 // Make me compile! Execute `rustlings hint functions1` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     call_me();
 }
+fn call_me() {
+    println!("Called!");
+}
diff --git a/exercises/functions/functions2.rs b/exercises/functions/functions2.rs
index 5721a17..6b73388 100644
--- a/exercises/functions/functions2.rs
+++ b/exercises/functions/functions2.rs
@@ -1,13 +1,11 @@
 // functions2.rs
 // Make me compile! Execute `rustlings hint functions2` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
-    call_me(3);
+    call_me(7);
 }
 
-fn call_me(num:) {
+fn call_me(num:i32) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }
diff --git a/exercises/functions/functions3.rs b/exercises/functions/functions3.rs
index ed5f839..475f401 100644
--- a/exercises/functions/functions3.rs
+++ b/exercises/functions/functions3.rs
@@ -1,10 +1,8 @@
 // functions3.rs
 // Make me compile! Execute `rustlings hint functions3` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
-    call_me();
+    call_me(6);
 }
 
 fn call_me(num: u32) {
diff --git a/exercises/functions/functions4.rs b/exercises/functions/functions4.rs
index 58637e4..b6af7c4 100644
--- a/exercises/functions/functions4.rs
+++ b/exercises/functions/functions4.rs
@@ -4,14 +4,12 @@
 // This store is having a sale where if the price is an even number, you get
 // 10 Rustbucks off, but if it's an odd number, it's 3 Rustbucks off.
 
-// I AM NOT DONE
-
 fn main() {
     let original_price = 51;
     println!("Your sale price is {}", sale_price(original_price));
 }
 
-fn sale_price(price: i32) -> {
+fn sale_price(price: i32) -> i32 {
     if is_even(price) {
         price - 10
     } else {
diff --git a/exercises/functions/functions5.rs b/exercises/functions/functions5.rs
index d22aa6c..b028976 100644
--- a/exercises/functions/functions5.rs
+++ b/exercises/functions/functions5.rs
@@ -1,13 +1,17 @@
 // functions5.rs
 // Make me compile! Execute `rustlings hint functions5` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     let answer = square(3);
     println!("The answer is {}", answer);
 }
 
+// without ; the expression is a return statement
+// it can be either both num * num or 
+// return num * num; 
+// but it cannot be
+// return num * num OR num * num;
+
 fn square(num: i32) -> i32 {
-    num * num;
+    num * num
 }
diff --git a/exercises/generics/generics1.rs b/exercises/generics/generics1.rs
index 967287e..07a3ed8 100644
--- a/exercises/generics/generics1.rs
+++ b/exercises/generics/generics1.rs
@@ -1,9 +1,7 @@
 // This shopping list program isn't compiling!
 // Use your knowledge of generics to fix it.
 
-// I AM NOT DONE
-
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list: Vec<&str> = Vec::new();
     shopping_list.push("milk");
 }
diff --git a/exercises/generics/generics2.rs b/exercises/generics/generics2.rs
index 0cb59ad..7f6cc2d 100644
--- a/exercises/generics/generics2.rs
+++ b/exercises/generics/generics2.rs
@@ -1,14 +1,12 @@
 // This powerful wrapper provides the ability to store a positive integer value.
 // Rewrite it using generics so that it supports wrapping ANY type.
 
-// I AM NOT DONE
-
-struct Wrapper {
-    value: u32,
+struct Wrapper<T> {
+    value: T,
 }
-
-impl Wrapper {
-    pub fn new(value: u32) -> Self {
+// <T> must be both for impl and Wrapper
+impl<T> Wrapper<T> {
+    pub fn new(value: T) -> Self {
         Wrapper { value }
     }
 }
diff --git a/exercises/generics/generics3.rs b/exercises/generics/generics3.rs
index 64dd9bc..b7a531e 100644
--- a/exercises/generics/generics3.rs
+++ b/exercises/generics/generics3.rs
@@ -10,15 +10,15 @@
 
 // Execute 'rustlings hint generics3' for hints!
 
-// I AM NOT DONE
-
-pub struct ReportCard {
-    pub grade: f32,
+pub struct ReportCard<T> {
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+// <T> must implement std::fmt::Display or no format!() macro
+// for you
+impl<T: std::fmt::Display> ReportCard<T> {
     pub fn print(&self) -> String {
         format!("{} ({}) - achieved a grade of {}",
             &self.student_name, &self.student_age, &self.grade)
@@ -46,7 +46,7 @@ mod tests {
     fn generate_alphabetic_report_card() {
         // TODO: Make sure to change the grade here after you finish the exercise.
         let report_card = ReportCard {
-            grade: 2.1,
+            grade: "A+".to_string(),
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };
diff --git a/exercises/if/if1.rs b/exercises/if/if1.rs
index 9086754..5761e7d 100644
--- a/exercises/if/if1.rs
+++ b/exercises/if/if1.rs
@@ -1,13 +1,16 @@
 // if1.rs
 
-// I AM NOT DONE
-
-pub fn bigger(a: i32, b: i32) -> i32 {
     // Complete this function to return the bigger number!
     // Do not use:
     // - another function call
     // - additional variables
     // Execute `rustlings hint if1` for hints
+pub fn bigger(a: i32, b: i32) -> i32 {
+    if a > b {
+        a
+    } else {
+        b
+    }
 }
 
 // Don't mind this for now :)
diff --git a/exercises/if/if2.rs b/exercises/if/if2.rs
index 80effbd..4d1ab2d 100644
--- a/exercises/if/if2.rs
+++ b/exercises/if/if2.rs
@@ -4,13 +4,14 @@
 // Step 2: Get the bar_for_fuzz and default_to_baz tests passing!
 // Execute the command `rustlings hint if2` if you want a hint :)
 
-// I AM NOT DONE
 
 pub fn fizz_if_foo(fizzish: &str) -> &str {
     if fizzish == "fizz" {
         "foo"
+    } else if fizzish == "fuzz" {
+        "bar"
     } else {
-        1
+        "baz"
     }
 }
 
diff --git a/exercises/modules/modules1.rs b/exercises/modules/modules1.rs
index 812dfee..7881573 100644
--- a/exercises/modules/modules1.rs
+++ b/exercises/modules/modules1.rs
@@ -1,10 +1,12 @@
 // modules1.rs
 // Make me compile! Execute `rustlings hint modules1` for hints :)
 
-// I AM NOT DONE
+// `mod` defines a module which can contain functions, structs etc.
+// by default, its `fn`s only limited within itself, creating "closed
+// ecosystem". you can make them public with `pub`
 
 mod sausage_factory {
-    fn make_sausage() {
+    pub fn make_sausage() {
         println!("sausage!");
     }
 }
diff --git a/exercises/modules/modules2.rs b/exercises/modules/modules2.rs
index fde439d..50a3f08 100644
--- a/exercises/modules/modules2.rs
+++ b/exercises/modules/modules2.rs
@@ -1,11 +1,9 @@
 // modules2.rs
 // Make me compile! Execute `rustlings hint modules2` for hints :)
 
-// I AM NOT DONE
-
 mod delicious_snacks {
-    use self::fruits::PEAR as fruit;
-    use self::veggies::CUCUMBER as veggie;
+    pub use self::fruits::PEAR as fruit;
+    pub use self::veggies::CUCUMBER as veggie;
 
     mod fruits {
         pub const PEAR: &'static str = "Pear";
diff --git a/exercises/move_semantics/move_semantics1.rs b/exercises/move_semantics/move_semantics1.rs
index e2f5876..78e4f8a 100644
--- a/exercises/move_semantics/move_semantics1.rs
+++ b/exercises/move_semantics/move_semantics1.rs
@@ -1,12 +1,11 @@
 // move_semantics1.rs
 // Make me compile! Execute `rustlings hint move_semantics1` for hints :)
 
-// I AM NOT DONE
 
 fn main() {
     let vec0 = Vec::new();
 
-    let vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(vec0);
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
diff --git a/exercises/move_semantics/move_semantics2.rs b/exercises/move_semantics/move_semantics2.rs
index bd21fbb..67e406d 100644
--- a/exercises/move_semantics/move_semantics2.rs
+++ b/exercises/move_semantics/move_semantics2.rs
@@ -2,12 +2,10 @@
 // Make me compile without changing line 13!
 // Execute `rustlings hint move_semantics2` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     let vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(&vec0);
 
     // Do not change the following line!
     println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
@@ -17,8 +15,8 @@ fn main() {
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
-    let mut vec = vec;
+fn fill_vec(vec: &[i32]) -> Vec<i32> {
+    let mut vec = vec.to_vec();
 
     vec.push(22);
     vec.push(44);
diff --git a/exercises/move_semantics/move_semantics3.rs b/exercises/move_semantics/move_semantics3.rs
index 43fef74..c9079a8 100644
--- a/exercises/move_semantics/move_semantics3.rs
+++ b/exercises/move_semantics/move_semantics3.rs
@@ -3,12 +3,10 @@
 // (no lines with multiple semicolons necessary!)
 // Execute `rustlings hint move_semantics3` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     let vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(&vec0);
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
@@ -17,7 +15,8 @@ fn main() {
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+fn fill_vec(vec: &[i32]) -> Vec<i32> { 
+    let mut vec = vec.to_vec();
     vec.push(22);
     vec.push(44);
     vec.push(66);
diff --git a/exercises/move_semantics/move_semantics4.rs b/exercises/move_semantics/move_semantics4.rs
index 2a23c71..c4999a9 100644
--- a/exercises/move_semantics/move_semantics4.rs
+++ b/exercises/move_semantics/move_semantics4.rs
@@ -4,12 +4,11 @@
 // freshly created vector from fill_vec to its caller.
 // Execute `rustlings hint move_semantics4` for hints!
 
-// I AM NOT DONE
 
 fn main() {
-    let vec0 = Vec::new();
+   // let vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec();
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
@@ -20,7 +19,7 @@ fn main() {
 
 // `fill_vec()` no longer takes `vec: Vec<i32>` as argument
 fn fill_vec() -> Vec<i32> {
-    let mut vec = vec;
+    let mut vec = Vec::new();
 
     vec.push(22);
     vec.push(44);
diff --git a/exercises/primitive_types/primitive_types1.rs b/exercises/primitive_types/primitive_types1.rs
index 0912139..2973cbf 100644
--- a/exercises/primitive_types/primitive_types1.rs
+++ b/exercises/primitive_types/primitive_types1.rs
@@ -2,8 +2,6 @@
 // Fill in the rest of the line that has code missing!
 // No hints, there's no tricks, just get used to typing these :)
 
-// I AM NOT DONE
-
 fn main() {
     // Booleans (`bool`)
 
@@ -12,7 +10,7 @@ fn main() {
         println!("Good morning!");
     }
 
-    let // Finish the rest of this line like the example! Or make it be false!
+    let is_evening = true; // Finish the rest of this line like the example! Or make it be false!
     if is_evening {
         println!("Good evening!");
     }
diff --git a/exercises/primitive_types/primitive_types2.rs b/exercises/primitive_types/primitive_types2.rs
index 6576a4d..def15a4 100644
--- a/exercises/primitive_types/primitive_types2.rs
+++ b/exercises/primitive_types/primitive_types2.rs
@@ -2,8 +2,6 @@
 // Fill in the rest of the line that has code missing!
 // No hints, there's no tricks, just get used to typing these :)
 
-// I AM NOT DONE
-
 fn main() {
     // Characters (`char`)
 
@@ -16,7 +14,7 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
+    let your_character = 'D'; // Finish this line like the example! What's your favorite character?
     // Try a letter, try a number, try a special character, try a character
     // from a different language than your own, try an emoji!
     if your_character.is_alphabetic() {
diff --git a/exercises/primitive_types/primitive_types3.rs b/exercises/primitive_types/primitive_types3.rs
index aaa518b..33d1a44 100644
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -2,10 +2,9 @@
 // Create an array with at least 100 elements in it where the ??? is.
 // Execute `rustlings hint primitive_types3` for hints!
 
-// I AM NOT DONE
 
 fn main() {
-    let a = ???
+    let a: [i32; 300] = [0; 300]; 
 
     if a.len() >= 100 {
         println!("Wow, that's a big array!");
diff --git a/exercises/primitive_types/primitive_types4.rs b/exercises/primitive_types/primitive_types4.rs
index 10b553e..d773c13 100644
--- a/exercises/primitive_types/primitive_types4.rs
+++ b/exercises/primitive_types/primitive_types4.rs
@@ -2,13 +2,11 @@
 // Get a slice out of Array a where the ??? is so that the test passes.
 // Execute `rustlings hint primitive_types4` for hints!!
 
-// I AM NOT DONE
-
 #[test]
 fn slice_out_of_array() {
     let a = [1, 2, 3, 4, 5];
 
-    let nice_slice = ???
+    let nice_slice = &a[1..4];
 
     assert_eq!([2, 3, 4], nice_slice)
 }
diff --git a/exercises/primitive_types/primitive_types5.rs b/exercises/primitive_types/primitive_types5.rs
index 680d8d2..85f42cf 100644
--- a/exercises/primitive_types/primitive_types5.rs
+++ b/exercises/primitive_types/primitive_types5.rs
@@ -2,11 +2,9 @@
 // Destructure the `cat` tuple so that the println will work.
 // Execute `rustlings hint primitive_types5` for hints!
 
-// I AM NOT DONE
-
 fn main() {
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    let (name, age) = cat;
 
     println!("{} is {} years old.", name, age);
 }
diff --git a/exercises/primitive_types/primitive_types6.rs b/exercises/primitive_types/primitive_types6.rs
index b8c9b82..48ee2da 100644
--- a/exercises/primitive_types/primitive_types6.rs
+++ b/exercises/primitive_types/primitive_types6.rs
@@ -2,14 +2,11 @@
 // Use a tuple index to access the second element of `numbers`.
 // You can put the expression for the second element where ??? is so that the test passes.
 // Execute `rustlings hint primitive_types6` for hints!
-
-// I AM NOT DONE
-
 #[test]
 fn indexing_tuple() {
     let numbers = (1, 2, 3);
     // Replace below ??? with the tuple indexing syntax.
-    let second = ???;
+    let second = numbers.1;
 
     assert_eq!(2, second,
         "This is not the 2nd number in the tuple!")
diff --git a/exercises/quiz1.rs b/exercises/quiz1.rs
index 5c5c355..6f67fd7 100644
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -7,10 +7,16 @@
 // more than 40 at once, each apple only costs 1! Write a function that calculates
 // the price of an order of apples given the order amount. No hints this time!
 
-// I AM NOT DONE
-
 // Put your function here!
 // fn ..... {
+fn calculate_apple_price(amount: i32) -> i32 {
+    if amount > 40 {
+        1 * amount
+    } else {
+        2 * amount
+    }
+}
+
 
 // Don't modify this function!
 #[test]
diff --git a/exercises/quiz2.rs b/exercises/quiz2.rs
index de0dce9..37c33a5 100644
--- a/exercises/quiz2.rs
+++ b/exercises/quiz2.rs
@@ -7,8 +7,6 @@
 // you think each value is. That is, add either `string_slice` or `string`
 // before the parentheses on each line. If you're right, it will compile!
 
-// I AM NOT DONE
-
 fn string_slice(arg: &str) {
     println!("{}", arg);
 }
@@ -17,14 +15,14 @@ fn string(arg: String) {
 }
 
 fn main() {
-    ???("blue");
-    ???("red".to_string());
-    ???(String::from("hi"));
-    ???("rust is fun!".to_owned());
-    ???("nice weather".into());
-    ???(format!("Interpolation {}", "Station"));
-    ???(&String::from("abc")[0..1]);
-    ???("  hello there ".trim());
-    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
+    string_slice("blue");
+    string("red".to_string());
+    string(String::from("hi"));
+    string("rust is fun!".to_owned());
+    string("nice weather".into());
+    string(format!("Interpolation {}", "Station"));
+    string_slice(&String::from("abc")[0..1]);
+    string_slice("  hello there ".trim());
+    string("Happy Monday!".to_string().replace("Mon", "Tues"));
+    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
 }
diff --git a/exercises/strings/strings1.rs b/exercises/strings/strings1.rs
index 8090244..027f071 100644
--- a/exercises/strings/strings1.rs
+++ b/exercises/strings/strings1.rs
@@ -2,13 +2,13 @@
 // Make me compile without changing the function signature!
 // Execute `rustlings hint strings1` for hints ;)
 
-// I AM NOT DONE
-
 fn main() {
     let answer = current_favorite_color();
     println!("My current favorite color is {}", answer);
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    // .to_string uses fmt trait
+    // .to_owned works too
+    "blue".to_owned()
 }
diff --git a/exercises/strings/strings2.rs b/exercises/strings/strings2.rs
index 5a2ce74..cc2f3d7 100644
--- a/exercises/strings/strings2.rs
+++ b/exercises/strings/strings2.rs
@@ -2,8 +2,6 @@
 // Make me compile without changing the function signature!
 // Execute `rustlings hint strings2` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     let word = String::from("green"); // Try not changing this line :)
     if is_a_color_word(word) {
@@ -13,6 +11,6 @@ fn main() {
     }
 }
 
-fn is_a_color_word(attempt: &str) -> bool {
+fn is_a_color_word(attempt: String) -> bool {
     attempt == "green" || attempt == "blue" || attempt == "red"
 }
diff --git a/exercises/structs/structs1.rs b/exercises/structs/structs1.rs
index 6d0b2f4..651a0c2 100644
--- a/exercises/structs/structs1.rs
+++ b/exercises/structs/structs1.rs
@@ -1,13 +1,12 @@
 // structs1.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
-
 struct ColorClassicStruct {
-    // TODO: Something goes here
+    name: String,
+    hex: String
 }
 
-struct ColorTupleStruct(/* TODO: Something goes here */);
+struct ColorTupleStruct(String, String);
 
 #[derive(Debug)]
 struct UnitStruct;
@@ -19,8 +18,10 @@ mod tests {
     #[test]
     fn classic_c_structs() {
         // TODO: Instantiate a classic c struct!
-        // let green =
-
+        let green = ColorClassicStruct { 
+            name: String::from("green"), 
+            hex: String::from("#00FF00")
+        };
         assert_eq!(green.name, "green");
         assert_eq!(green.hex, "#00FF00");
     }
@@ -28,7 +29,7 @@ mod tests {
     #[test]
     fn tuple_structs() {
         // TODO: Instantiate a tuple struct!
-        // let green =
+        let green = ColorTupleStruct("green".to_string(),"#00FF00".to_string());
 
         assert_eq!(green.0, "green");
         assert_eq!(green.1, "#00FF00");
@@ -37,7 +38,7 @@ mod tests {
     #[test]
     fn unit_structs() {
         // TODO: Instantiate a unit struct!
-        // let unit_struct =
+        let unit_struct = UnitStruct;
         let message = format!("{:?}s are fun!", unit_struct);
 
         assert_eq!(message, "UnitStructs are fun!");
diff --git a/exercises/structs/structs2.rs b/exercises/structs/structs2.rs
index f9c6427..df2e265 100644
--- a/exercises/structs/structs2.rs
+++ b/exercises/structs/structs2.rs
@@ -1,8 +1,6 @@
 // structs2.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Order {
     name: String,
@@ -34,7 +32,15 @@ mod tests {
     fn your_order() {
         let order_template = create_order_template();
         // TODO: Create your own order using the update syntax and template above!
-        // let your_order =
+        let your_order = Order {
+            name: String::from("Hacker in Rust"),
+            year: 2019,
+            made_by_phone: false,
+            made_by_mobile: false,
+            made_by_email: true,
+            item_number: 123,
+            count: 1,
+        };
         assert_eq!(your_order.name, "Hacker in Rust");
         assert_eq!(your_order.year, order_template.year);
         assert_eq!(your_order.made_by_phone, order_template.made_by_phone);
diff --git a/exercises/structs/structs3.rs b/exercises/structs/structs3.rs
index 8d8b471..b2b2bbc 100644
--- a/exercises/structs/structs3.rs
+++ b/exercises/structs/structs3.rs
@@ -4,7 +4,6 @@
 // Make the code compile and the tests pass!
 // If you have issues execute `rustlings hint structs3`
 
-// I AM NOT DONE
 
 #[derive(Debug)]
 struct Package {
@@ -16,7 +15,7 @@ struct Package {
 impl Package {
     fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
         if weight_in_grams <= 0 {
-            // Something goes here...
+            panic!("Weight is in negative value.");
         } else {
             return Package {
                 sender_country,
@@ -26,12 +25,20 @@ impl Package {
         }
     }
 
-    fn is_international(&self) -> ??? {
-        // Something goes here...
+    fn is_international(&self) -> bool {
+        if self.sender_country != self.recipient_country {
+            true
+        } else {
+            false
+        }
     }
 
-    fn get_fees(&self, cents_per_gram: i32) -> ??? {
-        // Something goes here... 
+    fn get_fees(&self, cents_per_gram: i32) -> i32 {
+        if cents_per_gram <= 0 {
+            panic!("We don't pay people, do we?");
+        } else {
+            cents_per_gram * self.weight_in_grams
+        }
     }
 }
 
@@ -73,7 +80,7 @@ mod tests {
         let sender_country = String::from("Spain");
         let recipient_country = String::from("Spain");
 
-        let cents_per_gram = ???;
+        let cents_per_gram = 3;
 
         let package = Package::new(sender_country, recipient_country, 1500);
 
diff --git a/exercises/variables/variables1.rs b/exercises/variables/variables1.rs
index 4a3af73..db85e7e 100644
--- a/exercises/variables/variables1.rs
+++ b/exercises/variables/variables1.rs
@@ -6,9 +6,7 @@
 // even after you already figured it out. If you got everything working and
 // feel ready for the next exercise, remove the `I AM NOT DONE` comment below.
 
-// I AM NOT DONE
-
 fn main() {
-    x = 5;
+    let x = 5;
     println!("x has the value {}", x);
 }
diff --git a/exercises/variables/variables2.rs b/exercises/variables/variables2.rs
index 7774a8f..be2ca14 100644
--- a/exercises/variables/variables2.rs
+++ b/exercises/variables/variables2.rs
@@ -1,10 +1,9 @@
 // variables2.rs
 // Make me compile! Execute the command `rustlings hint variables2` if you want a hint :)
 
-// I AM NOT DONE
 
 fn main() {
-    let x;
+    let x = 10;
     if x == 10 {
         println!("Ten!");
     } else {
diff --git a/exercises/variables/variables3.rs b/exercises/variables/variables3.rs
index 30ec48f..7d84709 100644
--- a/exercises/variables/variables3.rs
+++ b/exercises/variables/variables3.rs
@@ -1,10 +1,8 @@
 // variables3.rs
 // Make me compile! Execute the command `rustlings hint variables3` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
-    let x = 3;
+    let mut x = 3;
     println!("Number {}", x);
     x = 5; // don't change this line
     println!("Number {}", x);
diff --git a/exercises/variables/variables4.rs b/exercises/variables/variables4.rs
index 77f1e9a..7174d4f 100644
--- a/exercises/variables/variables4.rs
+++ b/exercises/variables/variables4.rs
@@ -1,9 +1,8 @@
 // variables4.rs
 // Make me compile! Execute the command `rustlings hint variables4` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
-    let x: i32;
+    let mut x: i32;
+    x = 512;
     println!("Number {}", x);
 }
diff --git a/exercises/variables/variables5.rs b/exercises/variables/variables5.rs
index da37ae9..10ef314 100644
--- a/exercises/variables/variables5.rs
+++ b/exercises/variables/variables5.rs
@@ -1,11 +1,9 @@
 // variables5.rs
 // Make me compile! Execute the command `rustlings hint variables5` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
     let number = "T-H-R-E-E";
     println!("Spell a Number : {}", number);
-    number = 3;
+    let number = 3;
     println!("Number plus two is : {}", number + 2);
 }
diff --git a/exercises/variables/variables6.rs b/exercises/variables/variables6.rs
index 9866691..ac322c3 100644
--- a/exercises/variables/variables6.rs
+++ b/exercises/variables/variables6.rs
@@ -1,9 +1,9 @@
 // variables6.rs
 // Make me compile! Execute the command `rustlings hint variables6` if you want a hint :)
 
-// I AM NOT DONE
-
-const NUMBER = 3;
+// consts have to have strict data type definition
+// otherwise they won't work
+const NUMBER: i32 = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }