Two persons A and B can complete a piece of work in 20 days and 40 days respectively. If they work together, what part of the work will be completed in 5 days? Choose the correct choice from the following
A) 1/8
B) 1/3
C) 3/6
D) 3/8
E) 5/3
A's one day's work = 1/20   B's one day's work = 1/40   (A + B)'s one day's work = 1/20 + 1/40 = 3/40   The part of the work completed in 5 days = 5 (3/40) = 3/8.   Answer:3/8
<result>D</result>
Two persons A and B can complete a piece of work in 20 days and 40 days respectively. If they work together, what part of the work will be completed in 5 days?