A works twice as fast as B. If B can complete a work in 12 days independently. The number of days in which A and B can together finish the work will be ______.

A. 4 days

B. 6 days

C. 8 days

D. 10 days

Explanation

If B takes 12 days to finish the work, then A takes 6 days to finish the same work.
If A can complete a work in x days and B can complete the same work in y days, then, both of them together can complete the work in x y/ x+ y days.
Therefore, the number of days taken by A and B together to finish the same work will be:
= 6 × 12/18= 4 days.

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