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?
.
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