diff --git a/src/functions-and-arrays.js b/src/functions-and-arrays.js
index 3a7dbec41..0bee89e8e 100644
--- a/src/functions-and-arrays.js
+++ b/src/functions-and-arrays.js
@@ -1,24 +1,78 @@
 // Iteration #1: Find the maximum
-function maxOfTwoNumbers() {}
-
-
+function maxOfTwoNumbers(number1, number2) {
+  if (number1 > number2) {
+    return number1;
+  }
+  else if (number1 < number2) {
+    return number2;
+  }
+  else {
+    return number1;
+  }
+}
 
 // Iteration #2: Find longest word
 const words = ['mystery', 'brother', 'aviator', 'crocodile', 'pearl', 'orchard', 'crackpot'];
 
-function findLongestWord() {}
-
-
+function findLongestWord(array) {
+  let LongestWordIndex = 0;
+  let LongestWordLength = 0;
+  if (array.length === 0) {
+    return null;
+  }
+  for(let i = 0; i < array.length; i++) {
+      if (i === 0) {
+        LongestWordLength = array[i].length;
+      } else {
+        if (array[i].length > LongestWordLength) {
+          LongestWordIndex = i;
+          LongestWordLength = array[i].length;
+        }
+      }
+  }
+  return array[LongestWordIndex];
+}
 
 // Iteration #3: Calculate the sum
 const numbers = [6, 12, 1, 18, 13, 16, 2, 1, 8, 10];
 
-function sumNumbers() {}
-
-
+function sumNumbers(array) {
+  let sum = 0;
+  for(let i = 0; i < array.length; i++) {
+    sum += array[i];
+  }
+  return sum;
+}
 
 // Iteration #3.1 Bonus:
-function sum() {}
+function sum(array) {
+  let sum = 0;
+  for (let i = 0; i < array.length; i++) {
+    const elementType = typeof array[i];
+    if (elementType !== "number" && elementType !== "string" && elementType !== "boolean") {
+      throw new Error("This element is not valid, it must be a number, a string or a boolean.");
+    }
+    else if (array.length === 0) {
+      return null;
+    }
+    else if (typeof array[i] === 'string') {
+      sum += array[i].length;
+    }
+    else if (typeof array[i] === 'boolean') {
+      if (array[i] === true) {
+        sum += 1;
+      }
+      else {
+        sum += 0;
+      }
+    } else if (typeof array[i] === 'number') {
+      sum += array[i];
+    } else if (typeof array[i] === 'object') {
+      sum += array[i].length
+    }
+  }
+  return sum;
+}
 
 
 
@@ -26,16 +80,55 @@ function sum() {}
 // Level 1: Array of numbers
 const numbersAvg = [2, 6, 9, 10, 7, 4, 1, 9];
 
-function averageNumbers() {}
+function averageNumbers(array) {
+  if (array.length === 0) {
+    return null;
+  } else {
+    let sum = sumNumbers(array);
+  return sum / array.length;
+  }
+}
 
 
 // Level 2: Array of strings
 const wordsArr = ['seat', 'correspond', 'linen', 'motif', 'hole', 'smell', 'smart', 'chaos', 'fuel', 'palace'];
 
-function averageWordLength() { }
+function averageWordLength(array) {
+  if (array.length === 0) {
+    return null;
+  }
+  else {
+      let sum = 0;
+    for(let i = 0; i < array.length; i++) {
+      sum += array[i].length;
+    }
+    return sum / array.length;
+  }
+}
 
 // Bonus - Iteration #4.1
-function avg() {}
+function avg(array) {
+  if (array.length === 0) {
+    return null;
+  }
+  let sum = 0;
+  for (let i = 0; i < array.length; i++) {
+    if (typeof array[i] === 'boolean') {
+      if (array[i] === true) {
+        sum += 1;
+      } else if (array[i] === false) {
+        sum += 0;
+      }
+    } else if (typeof array[i] === 'string') {
+      sum += array[i].length;
+    }
+      else if (typeof array[i] === "number") {
+        sum += array[i];
+      }
+  }
+  return sum / array.length;
+}
+
 
 // Iteration #5: Unique arrays
 const wordsUnique = [
@@ -52,14 +145,69 @@ const wordsUnique = [
   'bring'
 ];
 
-function uniquifyArray() {}
+function uniquifyArray(array) {
+  let nonRepitedWords = [];
+  nonRepitedWords.push(array[0]);
+  if (array.length === 0) {
+    return null;
+  }
+  else {
+    for (let i = 1; i < array.length; i++) {
+      if (!nonRepitedWords.includes(array[i])) {
+        nonRepitedWords.push(array[i]);
+      }
+    }
+  }
+  return nonRepitedWords;
+}
+
+/* Another solution:
+function uniquifyArray(array) {
+  let nonRepitedWords = [];
+  nonRepitedWords.push(array[0]);
+  if (array.length === 0) {
+    return null;
+  }
+  else {
+    for (let i = 1; i < array.length; i++) {
+      if (nonRepitedWords.indexOf(array[i]) == -1) {
+        nonRepitedWords.push(array[i]);
+      }
+    }
+  }
+  return nonRepitedWords;
+} */
+        
+/*!nonRepitedWords.includes(array[i])) {
+        nonRepitedWords += array[i];
+      }
+    }
+    return nonRepitedWords;
+  }
+  
+}*/
 
 
 
 // Iteration #6: Find elements
 const wordsFind = ['machine', 'subset', 'trouble', 'starting', 'matter', 'eating', 'truth', 'disobedience'];
 
-function doesWordExist() {}
+function doesWordExist(array, word) {
+  let checkedWord = 0;
+  if (array.length === 0) {
+    return null;
+  }
+  for(i = 0; i < array.length; i++) {
+    if (array[i] === word) {
+      checkedWord = true;
+      return checkedWord;
+    }
+    else {
+      checkedWord = false;
+    }
+  }
+  return checkedWord;
+}
 
 
 
@@ -78,8 +226,15 @@ const wordsCount = [
   'matter'
 ];
 
-function howManyTimes() {}
-
+function howManyTimes(array, word) {
+  let count = 0;
+  for (let i = 0; i < array.length; i++) {
+    if(word === array[i]) {
+      count += 1;
+    }
+  }
+  return count;
+}
 
 
 // Iteration #8: Bonus