P can do the work in 12 days and Q can do the same work in 20 days. If they work together for 4 days, what is the fraction of work that is left?	Pick one.
A) 7/15  B) 8/15  C) 11/15  D) 23/30  E) 41/60
4/12 + 4/20 = 1/3 + 1/5 = 8/15 (completed work)   The work that is left is 1 - 8/15 = 7/15   The answer is 7/15.
<result>A</result>
P can do the work in 12 days and Q can do the same work in 20 days. If they work together for 4 days, what is the fraction of work that is left?