Twelve men, working at 8 h a day, can do a piece of work in 18 days. In how many days can 24 men working at 6 h a day can do the same work?

24 men working at 8 hours per day can do a piece of work in 15 days. In how many days can 20 men working at 9 hours per day can complete the same work?

If 20 men working 7 hours a day can do a piece of work in 10 days, in how many days will 15 men working 8 hours a day do the same piece of work?

10 men working 8 hours day can do a work in 30 days. In how many days will 12 men working 4 hours a day take do the same work?

36 men can do a piece of work in 12 days. In how many days 9 men can do the same work?

8 men working for 9 hours a day can complete a piece of work in 20 days. In how many days can 7 men working for 10 hours a day complete the same piece of work?

If 52 men can do a piece of work in 35 days in how many days 28 men will do it ?