Two coal loading machines each working 12 hours per day for 8 days handle 9000 tonnes of coal with an efficiency of 90% while 3 other coal loading machines at an efficiency of 80% are set to handle 1200 tonnes of coals in 6 days. Find how many hours per day each should work.

4 men, each working 6 hours per day can build a wall in 9 days. How long will 6 men, each working 3 hours per day take to finish 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 10 men complete half work in 12 days when they work 8 hours per day, In how many days 18 men complete the full when they work 6 hours/day ?

2 men each working 5 hour per day can finish a job in 12 days. How long will 4 men each working 2 hours per day take to finish the same job?

iIf Shivaraj and Yashraj work 5 hours per day, they can do a certain piece of work in two days. If Yashraj and Jayraj work 5 hours per day, they can do that piece of work in days. Shivaraj and Jayraj intend to complete that piece of work in two days, they have to work 6 hours a day. If each of them alone is required to complete that piece of work, working five hours a day, in how many days would each of them complete the work?