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 is: Select the correct option
A) 60  B) 100  C) 120  D) 180  E) 200
Work done by the waste pipe in 1 min = 1/15-(1/20+1/24)   =-1/40   volume of whole = (3*40)= 
<gadget id="calculator">(3*40)</gadget>
<output>120</output>
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 is: