Question 146759: Cleaning Sidewalks. Edgar can blow the leaves off the sidewalks around the capitol building in 2 hours using a gasoline-powered blower. Ellen can do the same job in 8 hours using a broom. How long would it take them working together?
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! It's obvious you can't add the times, since 2 working would take less time. You have to look at the inverse.
Edgar can do 1 walk/2 hours, and Ellen can do 1 walk/8 hours. Add 1/2 and 1/8 to get 5/8. Then invert that, = 8/5.
Together it takes 1.6 hours, less than either of them separately. (Unless they yak too much, or spend time not working.)
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