Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank in gallons is?  Choose the correct option: A) 100 B) 110 C) 120 D) 140 E) 150
Let the total time taken by both the pipes be 120 minutes to fill the tank.   Therefore, the number of gallons filled by both the tanks in one minute = (6 + 5)= 
<gadget id="calculator">(6 + 5)</gadget>
<output>11</output>
11 gallons.   At the same time a waste pipe is also opened which can empty 3 gallons per minute.   Hence, the number of gallons filled in one minute= (11 - 3)= 
<gadget id="calculator">(11 - 3)</gadget>
<output>8</output>
8 gallons.   Therefore, the number of gallons filled when all the three pipes are opened for 15 minutes= 8 x 15 = 120 gallons.   ANSWER:120
<result>C</result>
Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank in gallons is?