Two pipes A and B can fill a tank in 36 hours and 45 hours respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?
A 20 hours
B 18 hours
C 25 hours
D 19 hours
Two pipes A and B can fill a tank in 36 hours and 45 hours respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?
A 20 hours
B 18 hours
C 25 hours
D 19 hours