X, Y and Z take 20, 30 and 60 days respectively to complete a job independently. They set out to complete a job together . However Y leaves after 4 days and Z leaves after another 6 days . How many more days will it take for X alone to complete the job now?

X is 25% more efficient than Y and his hourly wages are 25% more. If X is paid Rs.75, how much will Y receive for the same work?

Two outlets of the same capacity when opened together can empty a full tank of volume 3000 cu.m in 24 hr. If the tank is going to be filled by a tap at the rate of 300 cu.m/hr, what is the least number of additional outlets (which have the same capacity as the former outlets) that have to be opened, so that the tank never overflows?