Time and Work Questions

A work can be completed by 18 boys in 24 days. If 6 boys leave after working for 12 days, then how many days will be needed to complete the remaining work?

30 men working 5 hours a day can do a task in 16 days. In how many days will 40 men working 6 hours a day do the same task?

12 men or 30 boys can complete a work in 72 days. How many days will 48 men and 24 boys will take to complete the same work?

A certain number of men agreed to do a work in 20 days. 5 men did not come for work. Others completed the work in 40 days. Find the number of men who had agreed to do the work originally.

S does half as much work as T in 1/7 of the time taken by T. If together they take 21 days to complete a work, then how may days shall S take to complete that work alone?

U, V and W together can make a chair in 20 minutes. U and V together can make it in 25 minutes. How much time will (in minutes) W alone take to make the chair?

If a young son works quickly for 2 hours and prepares 16 items in a day, and his old father works slowly for 8 hours and prepares 24 items in a day, which of the following is true?

X can complete 5/7 part of a work in 10 days and Y can complete 3/4 part of the same work in 9 days. In how many days will both complete 13/21 part  of the total work?