Word Problem

Question

Working together, it takes two roofers 12 hours to put a new roof on a portable classroom. If the first roofer can do the job by himself in 16 hours, how many hours will it take the second roofer to do the job by himself

Answer 1

Working together:    1/12 roofs per hour

 

 

First roofer:  1/16 roofs per hour

 

X + 1/16 = 1/12

 

x = 1/12 - 1/16  = 4/48 - 3/48 = 1/48

 

Together, they work  1/48 + 1/16 = 1/48 + 3/48 = 4/48 = 1/12

 

It will take the second roofer 48 hours