If you and a friend have the same amount of apples, how many does she need to give you in order to have 10 more apples than her?
Answer
She needs to give you 5 apples.
You both need at least 5 apples to begin with, but apart from that it doesn’t matter exactly how many you each have. When she gives you 5 you will have 10 more than her because she will lose 5 and you will gain 5, resulting in a net difference of 10.
For example, if both of you have 20 apples and she gives you 5 of hers, she will be left with 15 and you will now have 25, precisely 10 more than she has.