Question

- A cistern has two inlets A and B which can fill it in 15 hours and 20 hours respectively. An outlet
empty the full cistern in 12 hours. If all the three pipes are opened together in the empty cistern, be
much time will they take to fill the cistern completely ?​

Answer 1

Answer:

1/15+1/20_1/12

4+3+5/60

12/60=5 hours