math
posted by Kelly on .
Joe and Bob manufacture bikes. Joe can make 12 bikes in 8 hours while Bob can make 6 bikes in 12 hours. Working together how many hours will it take them to make 12 bikes?
Please explain showing steps so I can learn it. I don't just need the answer. Thanks!

Joe 12 b/8 hr = 1.5 b/hr
Bob 6 b/12 hr = .5 b/hr
together 2 b/hr
2 b/hr * x hours = 12 b
x = 6 hours