A and B can do a piece of work in 12 days. B and C can do the same work in 15 days.

A and B can do a piece of work in 8 days, B and C can do the same work in 12 days. If A, B and C can complete the same work in 6 days, in how many days can A and C complete the same work?

A and B can do a piece of work in 8 days, B and C can do the same work in 12 days and A and C complete it in 8 days. In how many days A, B and C can complete the whole work, working together?

A and B can do a piece of work in 3 days. B and C can do the same workin 9days, while C and A can do it in 12 days. Find the time in which A, B and C can finish the work, working together.