math
posted by Kelly on .
Joe and Bob manufacture bikes. Joe can make 12 bikes in 8 hours while Bob can make 12 bikes in 6 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!
PS I originally typed the question wrong now it's correct.

joe's rate = 12 bikes/8 hrs or 1.5 bikes/hr
bob's rate = 12 miles/6 hrs or 2 bikes/hr
combined rate = 3.5 bikes/hr
time for 12 bikes = 12/(3.5) hrs = 3.42 hrs
or appr. 3 hrs and 26 minutes