Pipe A can fill a tank in 12 minutes,pipe B in 18 minutes and pipe C can empty the full tank in 36 minutes. If all of them are opend simultaneously, find the time taken to fill the empty tank.
The work done by the 3 pipe together in 1 minutes and `=(1)/(12)+(1)/(18)-(1)/(36)=(4)/(36)=(1)/(9)` So, the empty tank will be filled in 9 minutes
The work done by the 3 pipes together in 1 minute `=1//12+1//18-4//36=4//36=1//9`.
So, the empty tank will be filled in 9 minutes.