A, B and C can do one-third of a work in 15 days, 30 days and 10 days, respectively. A started the work. C joined him after 1 day and B joined them after 3 days of the beginning. For how many days did C work?
A and B together can complete a certain work in 20 days whereas B and C together can complete it in 24 days. If A is twice as good a workman as C, then in what time will B alone do 40% of the same work?