Two pumps are connected to an empty tank. Pump X fills the tank with water at a constant rate, while pump Y drains water out of the tank at a constant rate. The two pumps finish filling the tank in five times the duration it would take pump X alone to fill the tank. If pump Y alone can empty a whole tank in 45 minutes, then how many minutes does it take pump X alone to fill the tank? Choose the correct choice from the following choices:
A) 27
B) 30
C) 33
D) 36
E) 39
Let V be the volume of the tank.   Let R be the rate per minute that pump X fills the tank.   Let T be the time it takes pump X to fill the tank.   The rate at which pump Y empties the tank is V/45 per minute.   (R - V/45)*5T=V=RT.   (R-V/45)*5=R   4R=V/9.   R=V/36.   It takes pump X 36 minutes to fill the tank.   The answer is 36.
<result>D</result>
Two pumps are connected to an empty tank. Pump X fills the tank with water at a constant rate, while pump Y drains water out of the tank at a constant rate. The two pumps finish filling the tank in five times the duration it would take pump X alone to fill the tank. If pump Y alone can empty a whole tank in 45 minutes, then how many minutes does it take pump X alone to fill the tank?