I don't know why I can't figure this out but its KiLLiNg me

Question

john finished 24 math problems in one hour. at that rate, how many hours will it take him to complete 72 problems

Answer 1

Set up a rate of problems per hour. 24 problems per 1 hr is the rate.

An easy way to proceed is to just use a proportion. 24 problems in one hr is like 72 problems in x hrs or 24/1 = 72/x - then cross multiply giving 24x = 72, divide both sides by 24 to get x = 72/24 = 3