P is four times as fast as Q and working together, they can complete a work in 16 days. In how many days can Q alone complete the work?
Select the correct option.
A) 20 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 16 days, which means Q can do the work in 80 days.   Hence, P can do the work in 20 days.   20 daysNSWER:20 days
<result>A</result>
P is four times as fast as Q and working together, they can complete a work in 16 days. In how many days can Q alone complete the work?