Question 644426
    A pipe fills a tank in 8 hours. Another pipe empties the tank in 12 hours. If both pipes are opened together, how long will it take to fill the tank?
.
Let x = time (hours) it takes for both
then
x(1/8 + 1/12) = 1
multiplying both sides by 24:
x(3 + 2) = 24
x(5) = 24
x = 24/5
x = 4.8 hours
or
x = 4 hours and 48 minutes