A man and a boy together can do a certain amount of digging in 24 days. Their speeds in digging are in the ratio of 4 : 3. How many days will the boy take to complete the work if engaged alone?

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?