A can do 50% of a work in 20 days and B can do 6623% of the same work in 40 days. Both work together for 6 days. The remaining work is completed by C alone in 12 days. Working together, A, B and C will complete the same work in:

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?