a certain number of men could do a piece work in 60..., Chain Rule, General Mathematics

Question:A certain number of men could do a piece of work in `60` days. If there were `8` more men, it could be finished in `10` days less. The number of men in the beginning were :

A `30` 
B `35` 
C `40` 
D `45`

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+ AnswerC

+ ExplanationLet `x` men can finish the work in `60` days.

Then, `(x + 8)` men can finish it in `50` days.

More men, less days (Indirect)

`:. x + 8 : x = 60 : 50` or

`(x + 8)/x = (60)/(50)` or

`50 (x + 8) = 60x ` or

`x = 40`.

`:.` Number of men in the beginning `= 40`.

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