Arithmetic Questions And Answers :: Time And Work: part2

6.A can do a piece of work in 14 days which B can do in 21 days. They begin together but 3 days before the completion of the work. A leaves off. The total number of days to complete the work is:

7.12 men or 18 women can reap a field in 14 days. The number of days that 8 men and 16 women will take to reap it, is:

8.A and B working separately can do a piece of work in 9 and 12 days respectively. If they work for a day alternately. A beginning, in how many days the work will be completed?