A and B can do a piece of work in 15 days and 20 days respectively. If they work together for 5 days

A. 1/3

B. 1/4

C. 1/5

D. 1/6

E. None of the above

Answer: A. 1/3

In 5 days, A and B together complete 5 * (1/15 + 1/20) = 5 * (7/60) = 7/12 of the work. Thus, 1 - 7/12 = 5/12 of the work is left.

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