diff --git a/arrays.js b/arrays.js
index 3811265..c1c450c 100644
--- a/arrays.js
+++ b/arrays.js
@@ -4,20 +4,37 @@
 **************************************************************/
 function sumArray(numbers) {
   //TODO: Add your code here
+
+
+  const sum = numbers.reduce((accumulator, currentValue) =>
+  accumulator + currentValue, 0);
+  return sum;
 }
-// console.log(sumArray([4, 3, 2, 5, -10]));
+  
+
+const numbersArray = [1,2,3,4,5];
+const result = sumArray(numbersArray);
+console.log(result);
+
+
 
 /**************************************************************
  Task 2:
   Create a function findFirstStringStartingWithA that receives an array of strings as a parameter
   and returns the first string that starts with the letter given letter.
 **************************************************************/
-function findFirstStringStartingWithLetter(letter, strings) {
+function findFirstStringStartingWithLetter(letter, strings)  {
   //TODO: Add your code here
+  const foundString  = strings.find((currentString) =>
+  currentString.startsWith(letter)
+);
+
+return foundString || null
 }
-// console.log(
-//   findFirstStringStartingWithLetter("h", ["Memory", "Hello", "Happy"])
-// );
+console.log(
+  findFirstStringStartingWithLetter("H", ["Memory", "Hello", "Happy"])
+
+);
 
 /**************************************************************
  Task 3:
@@ -26,16 +43,18 @@ function findFirstStringStartingWithLetter(letter, strings) {
 **************************************************************/
 function isPresentIncluded(presentName, presents) {
   //TODO: Add your code here
+  return presents.includes(presentName);
 }
-// console.log(
-//   isPresentIncluded("puzzle", [
-//     "Sparkling Surprise",
-//     "Enchanted Elegance",
-//     "Whimsical Wonder",
-//     "Joyful Jingle",
-//     "Puzzle",
-//   ])
-// );
+
+console.log(
+  isPresentIncluded("Puzzle", [
+    "Sparkling Surprise",
+    "Enchanted Elegance",
+    "Whimsical Wonder",
+    "Joyful Jingle",
+    "Puzzle",
+  ])
+);
 
 /**************************************************************
  Task 4:
@@ -44,21 +63,23 @@ function isPresentIncluded(presentName, presents) {
 **************************************************************/
 function sortStudentsAlphabetically(students) {
   //TODO: Add your code here
+  return students.sort().toString()
+  
 }
-// console.log(
-//   sortStudentsAlphabetically([
-//     "Eve",
-//     "Jasmia",
-//     "Husnia",
-//     "Grace",
-//     "Bob",
-//     "Charlie",
-//     "Alice",
-//     "Dave",
-//     "Um abbas",
-//     "Frank",
-//   ])
-// );
+console.log(
+  sortStudentsAlphabetically([
+    "Eve",
+    "Jasmia",
+    "Husnia",
+    "Grace",
+    "Bob",
+    "Charlie",
+    "Alice",
+    "Dave",
+    "Um abbas",
+    "Frank",
+  ])
+);
 
 /**************************************************************
   Task 5:
@@ -70,14 +91,24 @@ function sortStudentsAlphabetically(students) {
 **************************************************************/
 function separateOddEven(numbers) {
   //TODO: Add your code here
+  const odds = [];
+  const evens = [];
+  numbers.forEach((number) => {
+    if (number % 2 === 0) {
+      evens.push(number);
+    } else {
+      odds.push(number);
+    }
+  });
+  return [odds, evens];
 }
-// console.log(separateOddEven([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]));
+console.log(separateOddEven([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]));
 
 /**************************************************************
  Task 6:
   Create a function that takes two parameters: a code that represents an item, and an array of item codes, then removes the item with the given code from the system.
-  - Hint: Use the filter method.
-  - e.g
+  -Hint: Use the filter method.
+  - e.g 
  const items = [
    { code: '#153', name: 'Ball' },
    { code: '#147', name: 'Scissors' },
@@ -90,15 +121,19 @@ function separateOddEven(numbers) {
 **************************************************************/
 function removeItem(code, items) {
   //TODO: Add your code here
+  return items.filter((item) => item.code!== code);
 }
-// console.log(
-//   removeItem("#153", [
-//     { code: "#153", name: "Ball" },
-//     { code: "#147", name: "Scissors" },
-//     { code: "#249", name: "Pillow" },
-//     { code: "#149", name: "Tissue" },
-//   ])
-// );
+console.log(
+  removeItem("#153", [
+    { code: "#153", name: "Ball" },
+    { code: "#147", name: "Scissors" },
+    { code: "#249", name: "Pillow" },
+    { code: "#149", name: "Tissue" },
+  ])
+  
+  );
+  
+
 
 /**************************************************************
 Task 7:
@@ -145,14 +180,18 @@ Task 7:
 **************************************************************/
 function updateGrades(curve, students) {
   //TODO: Add your code here
+  return students.map((student) =>
+  students.type === "nerd"
+  ? {...student, grade : student.grade - curve}
+  :{...student, grade : student.grade + curve});
 }
-// console.log(
-//   updateGrades(10, [
-//     { firstName: "Jaber", lastName: "jabarbar", grade: 10, type: "regular" },
-//     { firstName: "Hamza", lastName: "Alhamazi", grade: 12, type: "regular" },
-//     { firstName: "Jasem", lastName: "Jamasmas", grade: 15, type: "nerd" },
-//     { firstName: "Kadhim", lastName: "Khadhmia", grade: 5, type: "regular" },
-//     { firstName: "Um Abbas", lastName: "IDK", grade: 20, type: "nerd" },
-//     { firstName: "Johny", lastName: "Micle", grade: 10, type: "regular" },
-//   ])
-// );
+console.log(
+  updateGrades(10, [
+    { firstName: "Jaber", lastName: "jabarbar", grade: 10, type: "regular" },
+    { firstName: "Hamza", lastName: "Alhamazi", grade: 12, type: "regular" },
+    { firstName: "Jasem", lastName: "Jamasmas", grade: 15, type: "nerd" },
+    { firstName: "Kadhim", lastName: "Khadhmia", grade: 5, type: "regular" },
+    { firstName: "Um Abbas", lastName: "IDK", grade: 20, type: "nerd" },
+    { firstName: "Johny", lastName: "Micle", grade: 10, type: "regular" },
+  ])
+);