Okay kiddo, let me try to explain weighted sum to you. Imagine you have a bag full of candies - some are chocolate, some are gummies, and some are lollipops.
Now let's say your mom tells you to place all the candies in a tray and you need to count how many candies you have altogether. But the thing is, your mom wants you to give different scores to different types of candies. So chocolate candies are worth 2 points, gummies are worth 1 point, and lollipops are worth 3 points.
To get the total score, you need to add up the scores for each type of candy you have. You take the number of chocolate candies, multiply it by 2, and add that to the number of gummies multiplied by 1, and the number of lollipops multiplied by 3.
This is called a weighted sum because the different types of candies have different weights or scores. It's like adding up a bunch of numbers, but some numbers are more important than others.
Does that make sense, kiddo?