Two pipes fills a tank in 12 hours and 15 hours respectively while a third pipe empties the tank in 18 hours. !f all three pipes operate simultaneously, in what time will the tank be full?
a) 10 hours
b) 10 10/17 hours
c) 11 hours
d) 9 hours
e) 12 1/17 hours
a) 10 hours
b) 10 10/17 hours
c) 11 hours
d) 9 hours
e) 12 1/17 hours