SOLUTION: A painter finished a house in 8 hours, assistant takes 10 hours to finish same job, how long would it take them to complete this job if they worked together ?

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Question 813210: A painter finished a house in 8 hours, assistant takes 10 hours to finish same job, how long would it take them to complete this job if they worked together ?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Their rates are added simply if they work simultaneously (or at least, that is the idea to use).

The painter: 1/8 jobs per hour
The assistant: 1/10 jobs per hour
Both together: 1%2F8%2B1%2F10=5%2F40%2B4%2F40=highlight%289%2F40%29

That is NINE jobs per FORTY hours. You want the time h in hours for both people to do 1 job.

highlight%28%289%2F40%29%2Ah=1%29
h=40%2F9=highlight%284%264%2F9%29 hours