The ratio of the efficiency of worker A to worker B is 5:3. When B works with a third worker, C, they complete a job in 12 days. When A and C work together, they complete the same job in 9 days. If C takes Y days to complete the job alone, what is the value of Y/3?

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?