P, Q, and R can finish a work in 5 days, 10 days, and 15 days respectively when working alone. P and Q work together on the first day, P and R work to...
Question
P, Q, and R can finish a work in 5 days, 10 days, and 15 days respectively when working alone. P and Q work together on the first day, P and R work together on the second day, and P and Q work together again on the third day. In how many days will the work be completed?