A work force of 50 men with a contractor can finish a piece of work in 5 months. In how many months the same work can be completed by 125 men?

A work-force of 420 men with a contractor can finish a certain piece of work in 9 months. How many extra men must he employ to complete the job in 7 months?

A work-force of 420 men with a contractor can finish a certain piece of work in 9 months. How many extra men must he employ to complete the job in 7 months?

If 40 men can finish a piece of work in 60 days. In how many days will 75 , men finish the same work ?

8 men can finish a piece of work in 15 hours.In how many hours can 20 men finish it?

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

36 men can do a piece of work in 7 days. How many men will do the same work in 42 days ?