adult education
posted by Janice on .
If Sam can do a job in 4 days that Lisa can do in 6 days and Tom can do in 2 days, how long would the job take if Sam, Lisa, and Tom worked together to complete it?

In 24 days, Sam can do six jobs, Lisa can do 4 jobs, and Tom can do 12.
If they worked together for 24 days, they could do 6+4+12 jobs, or 22 jobs.
So each job takes 24/22 days. 
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