(1). X started a work and left after working for 5 days. Then Y did the remaining work in 15 days. Had X left the work after working for 10 days, Y would have finished the remaining work in 5 days. In how many days can each of them working alone, to finish the whole work?

• (a). 12.5 and 25days
• (b). 10 and 25 days
• (c). 15 days 25 days
• (d). 13 and 25 days
• (e). None of these