A and B can finish a work in 20 days. A alone can do th of the work in 12 days. In how many days can B alone do it?

A, B and C can reap a field in days; B, C and D in 14 days; C, D and A in 18 days; D, A and B in 21 days. In what time can A, B, C and D together reap it?

A and B can polish the floors of a building in 10 days. A alone can do th of it in 12 days. In how many days can B alone polish the floor?

A and B can do a piece of work in 20 days and B in 15 days. They work together for 2 days and then A goes away. In how many days will B finish the remaining work?

A can do a piece of work in 40 days and B in 45 days. They work together for 10 days and then B goes away. In how many days will A finish the remaining work?