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A job, whereas A needs 20 days to finish and B needs 12 days to finish. If A did $x$ days first, then B finish the rest of the job, the job will take 14 days to finish. What is $x$

The answer is 5.

1 solution

Jeremy Galvagni
Aug 2, 2018

A does 1/20 of the job per day, B does 1/12 of the job per day.

In x days, A does x/20. In (14-x) days, B does (14-x)/12. To do the whole job then

$\frac{x}{20}+\frac{14-x}{12}=1$

$\frac{-1x}{30}+\frac{7}{6}=1$

$x=\boxed{5}$

Al-jabr is good

The answer is 5.

1 solution

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