<PRE><B>Question 77719</B>
Lea can groom the horses in her boarding stable in 5 hr, while Tran needs 4 hr.  How long will it take them to groom the horses if they work together?
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Lea DATA
Time = 5 hr/job ; Rate = 1/5 job/hr
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Tran DATA:
Time = 4 hr/job ; Rate = 1/4 job/hr
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Together DATA:
Time = x hr/job ; Rate = 1/x job/hr
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EQUATION:
rate + rate = rate together
1/5 + 1/4 = 1/x
9/20 = 1/x
x=20/9  (Time for both together to do the job)

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Cheers,
Stan H.</PRE>