Q. A can do a piece of work in 4 days and B can do it in 12 days. In how many days will they finish the work, both working together?
Answer: 3 days
Notes: A's 1 day's work $latex = \frac{1}{4}&s=1$ B's 1 day's work $latex = \frac{1}{12}&s=1$ (A + B)'s 1 day's work $latex = \frac{1}{4} + \frac{1}{12}&s=1$ $latex = \frac{3+1}{12} = \frac{4}{12} = \frac{1}{3}&s=1$ ∴ Required Time = 3 days Hence option [B] is correct answer.

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