Two pipes A and B can separately fill a tank in 10 and 15 minutes respectively. A third pipe C can drain off 20 liters of water per minute. If all the pipes are opened, the tank can be filled in 15 minutes. What is the capacity of the tank? Pick one
A) 150 liters	B) 540 liters	C) 200 liters	D) 560 liters	E) 580 liters
1/10 + 1/15 - 1/x   = 1/15   x = 10   10 * 20= 
<gadget id="calculator">10 * 20</gadget>
<output>200</output>
200   Answer:200 liters
<result>C</result>
Two pipes A and B can separately fill a tank in 10 and 15 minutes respectively. A third pipe C can drain off 20 liters of water per minute. If all the pipes are opened, the tank can be filled in 15 minutes. What is the capacity of the tank?