Question

Working​ together, it takes two roofers 10 hours to put a new roof on a portable classroom. if the first roofer can do the job by himself in 12 ​hours, how many hours will it take the second roofer to do the job by​ himself?

Answer 1

Well it sounds like you would have to multiply by 2, which is the amount of roofers, then subtract 12.

10 x 2 = 20

20 - 12 = 8

Hope this helped.