P alone can complete a job in 5 days. The work done by Q alone in one day is equal to one-fourth of the work done by P alone in one day. In how many days can the work be completed if P and Q work together? Choose the correct choice from the following options
A) 2.5	B) 3.0	C) 3.5	D) 4.0	E) 4.5
P's rate is 1/5   Q's rate is 1/20   The combined rate is 1/5 + 1/20 = 1/4   If they work together, the job will take 4 days.   The answer is 4.0.
<result>D</result>
P alone can complete a job in 5 days. The work done by Q alone in one day is equal to one-fourth of the work done by P alone in one day. In how many days can the work be completed if P and Q work together?