<PRE><B>Question 287709</B>
An experienced roofer can roof a house in 26 hours. A beginning roofer needs 39 hours to complete the same job. Find how long it takes for the two of them to do the job together
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Experienced rate = 1/26 roof/hr
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Beginner rate = 1/39 roof/hr
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Together rate = 1/x roof/hr
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Equation:
rate + rate = together rate
1/26 + 1/39 = 1/x
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Multiply thru by 26*39x to get:
39x + 26x = 26*39
65x = 26*39
x = 78/5 = 15.6 hrs. (time to finish the roof if they work together)
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Cheers,
Stan H.</PRE>