The answer is D. It costs $45 for each basketball Matt purchased, which is the greater cost per basketball.
If you use the formula, y^2-y^1 over x^2- x^1. (Linear equations formula btw) then you would have subtracted 180/4 from 90/2 which would have given you 90/2. If you divide 90 into two it’s gonna equal 45.☺️