<PRE><B>Question 264415</B>
Bart can complete his science task twice as quickly as Carl can. When they work together, the task takes 3 hours. How long would it take Carl to do the work alone?
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Bart rate = 1/x job/hr
Carl rate = 1/2x job/hr
Together rate = 1/3 job/hr
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Equation:
1/x + 1/2x = 1/3
Multiply thru by 6x to get:
6 + 3 = 2x
2x = 9
x = 4.5 hrs 
2x = 9 hrs (time for Carl to do the job alone)
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Cheers,
Stan H.</PRE>