<PRE><B>Question 170417</B>
BILL CAN BUILD A BOOKCASE IN 6 HOURS, BUT IT TAKES HIS FRIEND, DAVID, ONLY 4 HOURS TO BUILD THE SAME BOOKCASE. HOW LONG WILL IT TAKE THEM TO BUILD THE BOOKCASE IF THEY WORK TOGETHER? 
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Bill DATA:
Time = 6hrs/job ; rate = 1/6 job/hr
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Davis DATA::
Time = 4 hrs/job ; rate = 1/4 job/hr
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Together DATA:
Time = x hrs/job ; rate = 1/x job/hr
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EQUATION:
rate + rate = together rate
1/6 + 1/4 = 1/x
(10/24) = 1/x
x = 24/10 = 2.4 hrs
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0.4 hrs = 0.4*60 minutes = 24 minutes
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Answer: 2 hrs and 24 minutes (time they need to do the job together)
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Cheers,
Stan H.</PRE>