Two pipes fill a tank when working individually in 25 and 40 hours, respectively while a third pipe can drain the filled tank in 16 hours. If all the three pipes are turned on at the same time when the tank is empty, how long will it take to fill the tank completely?
1
15 days 18 hours
2
2 days 1 hour
3
16 days 16 hours
4
1 day 7 hours