Problem

A gas station sells refillable pop cups for $9. Each refill costs you $2. Last month Fred spend $30 on 1 pop cup and refills. How many refills did he buy.

Solution

The first thing you want to do is set up the problem in a way that is easy for you to solve like 30=9+2x or flip it 2x+9=30 and the way you would solve this is you would do 30-9 because it says for you to add but you’re supposed to minus so it would be 30-9=21 and then you would do 2x=21 and set it up like that, and after you have done that you divide 21/2 and that would be your answer to how many refills Fred bought. The answer is x=10.5 so he spent $10.50 on refills.