A and  B can do a piece of work in 12 days. B and C together can do it in 15 days. If A is twice as good a workman as C, find in what time B alone can do it.

A and B together can complete a piece complete a piece of work in 12 days , B and C together can complete it in 15 days. If A is twice as good a workman as C, in many days will A alone complete the same work ?

A and B can do a piece of work in 12 days, B and C in 15 days respectively. If A is twice as good as a workman as C, in how many days will A alone complete the same work?