SOLUTION: If two people work at washing 5 cars and one can do all 5 cars on their own in 36 minutes and the other can do all 5 on their own in 42 minutes, how long does it take to wash all 5

Question 1104644: If two people work at washing 5 cars and one can do all 5 cars on their own in 36 minutes and the other can do all 5 on their own in 42 minutes, how long does it take to wash all 5 working together?
Found 2 solutions by jorel1380, josgarithmetic:
Answer by jorel1380(3719) (Show Source): You can put this solution on YOUR website!
The first person does 5 cars in 36 minutes, or 5/36 car per minute. The second one does 5/42 car per minute. Together,:
5/36+5/42=5/n
35/252+30/252=5/n
35n+30n=1260
n=1260/65=252/13 min. working together
☺☺☺☺

Answer by josgarithmetic(39620) (Show Source): You can put this solution on YOUR website!
One job is wash five cars.

RATE of both people combined is JOBS per MINUTES.
Lowest common denominator is .

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TIME:

or about 20 minutes.
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