Question 727755
5 workers can do 3 jobs in 2 days.
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It will take 3 times as many workers to do 
3 times as many jobs in the same time, so
15 workers can do 9 jobs in 2 days
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In 5 times as many days, it will only take 1/5
as many workers to do the same number of jobs, so
3 workers can do 9 jobs in 10 days
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It will take twice as many workers to do twice as
many jobs in the same time, so
6 workers can do 18 jobs in 10 days