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) 887 gallons
B) 176 gallons
C) 120 gallons
D) 289 gallons
E) 976 gallons
Work done by the waste pipe in 1 minute   = 1/15 - (1/20 + 1/24) = - 1/40   Volume of 1/40 part   = 3 gallons   Volume of whole = 3 * 40= 
<gadget id="calculator">3 * 40</gadget>
<output>120</output>
120 gallons.   Answer:120 gallons
<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?