 
 <translate> 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 = 120 gallons. So the final answer is (C). <hau> Aikin da bututun sharar ya yi a cikin minti 1 = 1/15 - (1/20 + 1/24) = - 1/40 Volume na 1/40 kashi = 3 galan\ Volume na dukan = 3 * 40 = 120 galan. Saboda haka amsar ita ce (C). 