diff --git a/src/functions-and-arrays.js b/src/functions-and-arrays.js
index 3a7dbec41..7c3b898b5 100644
--- a/src/functions-and-arrays.js
+++ b/src/functions-and-arrays.js
@@ -1,41 +1,121 @@
 // Iteration #1: Find the maximum
-function maxOfTwoNumbers() {}
-
-
+function maxOfTwoNumbers(num1,num2) {
+  if (num1 > num2) {
+    return num1;
+  } else if (num1 < num2){
+    return num2;
+  } else {
+    return num1;
+  }
+}
 
 // Iteration #2: Find longest word
 const words = ['mystery', 'brother', 'aviator', 'crocodile', 'pearl', 'orchard', 'crackpot'];
 
-function findLongestWord() {}
-
-
+function findLongestWord(words) {
+  let longestWord = "" ;
+  if (words.length === 0) {
+    return null;
+  }
+  for (let i = 0; i < words.length; i++) {
+    if (words[i].length > longestWord.length) {
+      longestWord = words[i];
+    }
+  }
+  return longestWord;
+}
 
 // Iteration #3: Calculate the sum
 const numbers = [6, 12, 1, 18, 13, 16, 2, 1, 8, 10];
 
-function sumNumbers() {}
-
-
+function sumNumbers(numbers) {
+  let sum = 0;
+  if (numbers.length === 0) {
+    return 0;
+  }
+  for (let i = 0; i < numbers.length; i++){
+    sum += numbers[i];
+  }
+  return (sum);
+}
 
 // Iteration #3.1 Bonus:
-function sum() {}
-
-
-
+const mixedArr = [6, 12, 'miami', 1, true, 'barca', '200', 'lisboa', 8, 10];
+
+
+function sum(mixedArr) {
+  let sum = 0;
+  if (mixedArr.length === 0) {
+    return 0;
+  }
+  for (let i = 0; i < mixedArr.length; i++) {
+    if (typeof mixedArr[i] === "number") {
+      sum += mixedArr[i];
+    } else if (typeof mixedArr[i] === "string"){
+      sum += mixedArr[i].length;
+    } else if (typeof mixedArr[i] === "boolean"){
+       if (mixedArr[i] === true) {
+        sum += 1;
+       } else {
+        sum += 0;
+       }
+    } else {
+      throw new Error("That value is not a number, string o boolean");
+    }
+    }
+    return sum;
+  }
 // Iteration #4: Calculate the average
 // Level 1: Array of numbers
 const numbersAvg = [2, 6, 9, 10, 7, 4, 1, 9];
 
-function averageNumbers() {}
-
+function averageNumbers(numbersAvg) {
+  let sum = 0;
+  if (numbersAvg.length === 0) {
+    return null;
+  }
+  for (let i = 0; i < numbersAvg.length; i++){
+    sum += numbersAvg[i];
+  }
+  return sum / numbersAvg.length;
+}
 
 // Level 2: Array of strings
 const wordsArr = ['seat', 'correspond', 'linen', 'motif', 'hole', 'smell', 'smart', 'chaos', 'fuel', 'palace'];
 
-function averageWordLength() { }
+function averageWordLength(wordsArr) {
+let sum = 0;
+if (wordsArr.length === 0) {
+  return null;
+}
+for (let i = 0; i < wordsArr.length; i++){
+  sum += wordsArr[i].length;
+}
+return sum / wordsArr.length;
+}
 
 // Bonus - Iteration #4.1
-function avg() {}
+const arr = [6, 12, 'miami', 1, true, 'barca', '200', 'lisboa', 8, 10];
+function avg(arr) {
+  let sum = 0;
+  if (arr.length === 0) {
+    return null;
+  }
+  for (let i = 0; i < arr.length ; i++){
+    if (typeof arr[i] === "number") {
+      sum += arr[i];
+    } else if (typeof arr[i] === "string"){
+      sum += arr[i].length;
+    } else if (typeof arr[i] === "boolean"){
+      if (arr[i] === true) {
+        sum += 1;
+       } else {
+        sum += 0;
+       }
+    }
+  }
+ return sum / arr.length ;
+}
 
 // Iteration #5: Unique arrays
 const wordsUnique = [
@@ -52,16 +132,34 @@ const wordsUnique = [
   'bring'
 ];
 
-function uniquifyArray() {}
-
-
+function uniquifyArray(wordsUniqu) {
+  let newArr = [];
+  if (wordsUniqu.length === 0) {
+    return null;
+  }
+  for (let i = 0; i < wordsUniqu.length; i++) {
+    if (!newArr.includes(wordsUniqu[i])) {
+      newArr.push(wordsUniqu[i]);
+    }
+  }
+  return newArr;
+}
 
 // Iteration #6: Find elements
 const wordsFind = ['machine', 'subset', 'trouble', 'starting', 'matter', 'eating', 'truth', 'disobedience'];
 
-function doesWordExist() {}
-
-
+function doesWordExist(wordsFind, word) {
+  if (wordsFind.length === 0) {
+    return null;
+  }
+  for (let i = 0; i < wordsFind.length; i++){
+    if (wordsFind.includes(word)){ // perguntar pq no puedo poner wordsFind[i], como en el caso anterior. ?! 
+      return true;
+    } else {
+      return false;
+    }
+  }
+}
 
 // Iteration #7: Count repetition
 const wordsCount = [
@@ -78,10 +176,19 @@ const wordsCount = [
   'matter'
 ];
 
-function howManyTimes() {}
-
-
-
+function howManyTimes(wordsCount, words) {
+  let newCount = 0;
+  if (wordsCount.length === 0){
+    return 0;
+  } else {
+    for (let i = 0; i < wordsCount.length; i++){
+      if (wordsCount[i] == words) {
+        newCount++;
+      }
+    }
+    return newCount;
+  }
+}
 // Iteration #8: Bonus
 const matrix = [
   [8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8],