X is able to complete a task in 12 days, while Y takes 18 days to finish the same task. If they collaborate and work together for 3 days, what fraction of the work will still remain?

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Accepted Answer

1. X's rate is $\frac{1}{12}$ work/day and Y's rate is $\frac{1}{18}$ work/day.
2. Together their rate is $\frac{1}{12}+\frac{1}{18}=\frac{5}{36}$ work/day.
3. In 3 days they do $3	imes\frac{5}{36}=\frac{15}{36}=\frac{5}{12}$ of the work.
4. Remaining work is $1-\frac{5}{12}=\frac{7}{12}$.

FINAL_ANSWER: c

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Answer

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