A and B can do a piece of work in 12 days and 15 days respectively. How long will they take to complete the work if A works alone for 4 days and then B joins him?
If A can finish a work in 24 days and B can finish the same work in 36 days, how long will it take for them to finish the work if A works alone for 10 days and then B joins him?
A can do a work in 16 days, B can do the same work in 24 days, and C can do it in 32 days. If they all work together, how long will it take to complete the work?