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Question 4220: It takes you 6 hours to do a job. It takes a friend 3 hours to do the same job. How long would it take both of you working together to do the job?
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! If you can do a job in 6 hours, then in 1 hour you can do  of the job.
If your friend can do the same job in 3 hours, then in 1 hour he/she can do  of the job.
Let x = the time it would take you to do the job working together.
Then in 1 hour, together you could do 1/x of the job.
So, the equation is that what you can do in 1 hour, plus what your friend can do in 1 hour, equals what you can do together in 1 hour, or as follows:
This equation can be solved in two ways. For those who do NOT like fractions, you can multiply both sides of the equation by the Least Common Denominator (LCD), which in the case is 6x:
Reduce all the fractions, which eliminates all the denominators:
R^2 at SCC
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