SOLUTION: One person can do a certain job in twenty-one minutes, and another person can do the same job in twenty-eight minutes. How many minutes will it take them to do the job altogether?

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Question 121668: One person can do a certain job in twenty-one minutes, and another person can do the same job in twenty-eight minutes. How many minutes will it take them to do the job altogether?
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
21*28/(21+28)=588/49=12 MINUTES TO COMPLETE THE JOB WORKING TOGETHER.