SOLUTION: A pipe can fill a tank in 30minutes and another pipe can make empty the tank in 45 minutes. How much time it takes to empty the tank if both are working together.

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Question 531348: A pipe can fill a tank in 30minutes and another pipe can make empty the tank in
45 minutes. How much time it takes to empty the tank if both are working together.

Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
A pipe can fill a tank in 30minutes and another pipe can make empty the tank in
45 minutes. How much time it takes to empty the tank if both are working together.
assuming the tank was completely filled at the start then:
Let x = time (minutes) to empty tank
then
x(1/30 - 1/45) = 1
multiplying both sides by 90:
x(3 - 2) = 90
x(1) = 90
x = 90 minutes