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	Choose the most appropriate option.
A) 100 gallons
B) 110 gallons
C) 120 gallons
D) 130 gallons
E) 140 gallons
Work done by the waste pipe in 1 minute = 1/15-(1/20+1/24)   = -1/40[-ve means emptying]   so, 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