Two persons A and B can do a piece of work in 45 and 40 days respectively. They started the work together, but A left after some days and the remaining work was completed by B in 23 days. After how many days did A leave?

A11

B10

D9 ✓ Correct

Correct answer: (D) 9

Explanation

A left after 9 days.

Let A work d days; B works d + 23 days in total.

Work equation: d/45 + (d + 23)/40 = 1.

Multiply by 360: 8d + 9(d + 23) = 360.

17d + 207 = 360, so 17d = 153 and d = 9.

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