Working alone, pump A can empty a pool in 6 hours. Working alone, pump B can empty the same pool in 9 hours. Working together, how many minutes will it take pump A and pump B to empty the pool?
Choose the correct choice from the following answers:
A) 192	B) 200	C) 208	D) 216	E) 224
Pump A can empty (1/6) of the pool per hour.   Pump B can empty (1/9) of the pool per hour.   Together the pumps can empty 1/6+1/9=5/18 of the pool per hour.   1 pool / (5/18) pool per hour = 18/5 hours = 216 minutes.   The answer is 216.
<result>D</result>
Working alone, pump A can empty a pool in 6 hours. Working alone, pump B can empty the same pool in 9 hours. Working together, how many minutes will it take pump A and pump B to empty the pool?