<PRE><B>Question 349097</B>
If it takes one worker 20 hours to roof a house and another 25 hours how long will it take them to work together?
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1st worker rate = 1/20 job/hr
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2nd worker rate = 1/25 job/hr
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Together rate = 1/x job/hr
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Equation:
rate + rate = together rate
1/20 + 1/25 = 1/x
5x + 4x = 100
9x = 100
x = 100/9 = 11 1/9 hrs (time to do the job together)
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Cheers,
Stan H.</PRE>