SOLUTION: You can paint a certain room in 3 hours. Your brother can do it in 4 hours. How long does it take the two of you working together?

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Question 311042: You can paint a certain room in 3 hours. Your brother can do it in 4 hours. How long does it take the two of you working together?
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
You can paint a certain room in 3 hours. Your brother can do it in 4 hours. How long does it take the two of you working together?
.
Let x = time for both to do job
then
x(1/3 + 1/4) = 1
multiplying both sides by 12:
x(4 + 3) = 12
7x = 12
x = 12/7 hours
or
x = 1 hour 43 minutes