P is four times as fast as Q and working together, they can complete a work in 20 days. In how many days can Q alone complete the work?
Choose the correct choice from the following answers
A) 35 days  B) 15 days  C) 16 days  D) 25 days  E) 18 days
P = 4Q   P + Q = 4Q + Q = 5Q   These 5Q people can do the work in 20 days, which means Q can do the work in 100 days.   Hence, P can do the work in 25 days.   ANSWER:25 days
<result>D</result>
P is four times as fast as Q and working together, they can complete a work in 20 days. In how many days can Q alone complete the work?