diff --git a/scripts/lab4.js b/scripts/lab4.js
index ce452ba..1111d99 100644
--- a/scripts/lab4.js
+++ b/scripts/lab4.js
@@ -6,15 +6,17 @@
  * @returns The sum of the two numbers if add is true and false otherwise.
  */
 function sumValues(num1, num2, add) {
-    if (add) {
-        const result = 0;
+     if (add === true) {
+        if (typeof num1 !== 'number' || typeof num2 !== 'number') {
+            return false;
+        }
 
         result = num1 + num2;
 
         return result;
     }
     else {
-        return !add;
+        return false;
     }
 }
 
@@ -25,15 +27,19 @@ function sumValues(num1, num2, add) {
  * @returns An array of each price's new price, after the discount is applied. Or false, if prices array is empty.
  */
 function discountPrices(prices, discount) {
+     if (!Array.isArray(prices) || typeof discount !== 'number') {
+        return false;
+    }
+    if (prices.length === 0) return false;
+    
     const discounted = []
-    const length = prices.length;
     let discountedPrice = 0
-    for(let i = 0; i < length; i++) {
-        discountedPrice += prices[i] * (1 - discount);
+    for (let i = 0; i < prices.length; i++) {
+        let discountedPrice = prices[i] * (1 - discount);
         discounted.push(discountedPrice);
     }
 
     return discounted;
 }
 
-module.exports = {sumValues, discountPrices};
\ No newline at end of file
+module.exports = {sumValues, discountPrices};