Pipes A and B together can fill an empty tank in 30 hours, whereas pipes B and C together can fill it in 24 hours. If pipes A, B, and C together can fill the tank in 20 hours, in how many hours can pipe B alone fill 35% of the tank?

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?