A can complete a piece of work alone in 120 days, while A and B, working together, can complete this piece of work in 72 days. In how many days can B, working alone, complete this piece of work?

Each inlet pipe can fill an empty cistern in 84 hours while each drain pipe can empty the same cistern from a filled condition in 105 hours. When the cistern is empty, 9 inlet pipes and 10 outlet pipes are simultaneously opened. After how many hours will the cistern be completely filled?

4 men’s work is equal to 6 women’s work, and 4 women’s work is equal to 6 boys’ work. A boy can finish the work in 60 days. In how many days can the work be finished by a man and a woman together?

A group of men decided to do a job in 11 days but 16 men left the work after each day. The work, as a result, got completed in 15 days. How many men were there initially in the group?