X and Y together can do a piece of work in 30 days. Y and Z together can do the work in 20 days. X starts the work and works for 15 days then Y takes that work and works for 27 days. Finally Z finishes the remaining work in 9 days. In how many days Y alone can complete the entire work?
P and Q together can make a door in 12 days. They started the work together but after 8 days P left the work. The remaining work is completed by Q alone in 7 more days. In how many days can P alone complete the entire work?