Arbaz and Aman can complete painting a building in 16 days and 12 days, respectively. If Arbaz starts the work and they work on alternate days, in how many days will the painting of the building be completed?

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?