A is twice as fast as B. If B alone can do a piece of work in 30 days, in what time can A and B together complete the work?	Answers:
A) 13 B) 10 C) 16 D) 50 E) 23
Option B   Explanation:   A can do the work in 30/2 i.e., 15 days.   A and 10's one day's work = 1/15 + 1/30 = (2 + 1)/30 = 1/10   So A and 10 together can do the work in 10 days.
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A is twice as fast as B. If B alone can do a piece of work in 30 days, in what time can A and B together complete the work?