Question

one pipe can fill in 45 minutes and another can fill it in 30 minutes. if these 2 pipes are open and a third pipe is draining water from the tank, it takes 27 minutes to fill the tank.how long will it take the third alone to empty a full tank?

Answer 1

So you need to solve 1/45+1/30-1/x=1/27 for x. The answer should be 54 minutes.