SOLUTION: a mechanic and his helper can repair a car in 7 hours. the helper takes twice as long as the mechanic. how long would it take the helper to make the repair working alone?

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Question 386500: a mechanic and his helper can repair a car in 7 hours. the helper takes twice as long as the mechanic. how long would it take the helper to make the repair working alone?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

Let x and 2x represent the solo times for the mechanic and helper respectivly

Question States:  Per hour being Equalizer

 1/x + 1/2x = 1/7 Mulitplying each term by 14x so as all denominators = 1

 14 + 7 = 2x

    21 = 2x

     x = 21/2 = 10.5hrs, mechanics solo time, the helper's 21hr   (2*10.5)



CHECKING our Answer

  1/10.5 + 1/21 = .1429 hr = 1/7