If 2 men and 3 boys can do a piece of work in 6 days, and 8 men and 5 boys can do the same work in 2 days, what is the ratio of the working capacity of a man to that of a boy?

If P and Q together can complete a piece of work in 15 days and P alone can do it in 45 days, in how many days can Q alone complete that work?

A can lay a railway track between two stations in 16 days and B can do the same job in 12 days. With the help of C, they finished the job in 4 days. In how many days can C alone do the job?