The work done by a woman in 6 h is equal to the work done by a man in 4 h and by a boy in 8 h. Working 8 h per day, if 8 women can complete a work in 10 days, then in how many days can 10 women, 10 men, and 10 boys together finish the same work working 8 h per day?

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?