Consider the question. 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?
Options:
(A) 1/8
(B) 1/3
(C) 3/6
(D) 3/8
(E) 5/3
What is the step-by-step reasoning process to arrive at the answer: (D)?
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.