Question 189865
Let x=amount of time it takes both pipes draining together to empty the pool

First pipe empties at the rate of 540,000/150=3600 liters/min
Second pipe empties at the rate of 540,000/225=2400 liters/min

Together, both pipes empties at the rate of 3600+2400=6000 liters/min, so our equation to solve is:

6000*x=540000

x=90 min------------------ans
CK
90*3600+90*2400=540000

324000+216000=540000
540000=540000


Hope this helps---ptaylor