<PRE><B>Question 82503</B>
Team A can set up chairs in the gym in 15 minutes and Team B can set up chairs in 20 minutes. How long would it take them, working together to set up the same chairs?
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Team A DATA:
Time = 15 min/job ; Rate = 1/15 job/min
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Team B DATA:
Time = 20 min/job ; Rate = 1/20 job/min
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Together DATA:
Time = x min/job ; Rate = 1/x job/min
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EQUATION:
rate + rate = together rate
1/15 + 1/20 = 1/x 
Multiply thru by 60x to get:
4x + 3x = 60
7x=60
x= 8.57 minutes/job
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0.57 min = 0.57*60 sec  = 34.2 seconds
Time working together is 8 min 34.2 seconds
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Cheers,
Stan H.
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