A man takes 16 days to complete a project and a woman takes 12 days to complete the same work. If they work together on alternate days, starting with the man on the first day, how many days will they take to complete the work?

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?