A can do a work in 10 days, B can do it in 15 days, and C can do it in 20 days. If they work togethe

A. 1/3

B. 1/4

C. 1/5

D. 1/6

E. None of the above

Answer: B. 1/4

In 2 days, A, B, and C together complete 2 * (1/10 + 1/15 + 1/20) = 2 * (1/6) = 1/3 of the work. Thus, 1 - 1/3 = 2/3 of the work is left.

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