A can do a work in 25 days and B in 20 days. They start together, but A leaves 5 days before the work is finished. In how many days is the work finished?

A. 15 days

B. \(13\frac{1}{3}\) days

C. \(11\frac{1}{3}\) days

D. 12 days

Doubtly AI Asked 27 Oct 2026 AI-generated · not yet verified ssc cgl Save WhatsApp Report

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Answer: B. \(13\frac{1}{3}\) days

Answer: (B) \(13\frac{1}{3}\) days

Let the total time be T days. A works (T − 5) days and B works T days.

\(\frac{T - 5}{25} + \frac{T}{20} = 1\) → 4(T − 5) + 5T = 100 → 9T = 120.

T = \(\frac{40}{3} = 13\tfrac{1}{3}\) days.

Shortcut: in the last 5 days only B works and does 5/20 = 1/4. The other 3/4 is done together at 9/100 per day, taking 25/3 days. Total = 25/3 + 5 = 40/3 days.

Doubtly AI · 27 Oct 2026 AI-generated · not yet verified Report

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A can do a work in 25 days and B in 20 days. They start together, but A leaves 5 days before the work is finished. In how many days is the work finished?

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