SOLUTION: Working together, Elisa and Chelsea can inflate twenty balloons in 6.96 minutes. Had she done it alone it would have taken Chelsea 15 minutes. find how long it would take Elisa to

Question 411792: Working together, Elisa and Chelsea can inflate twenty balloons in 6.96 minutes. Had she done it alone it would have taken Chelsea 15 minutes. find how long it would take Elisa to do it alone.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Working together, Elisa and Chelsea can inflate twenty balloons in 6.96 minutes. Had she done it alone it would have taken Chelsea 15 minutes. find how long it would take Elisa to do it alone.
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Together DATA:
time = 6.96 min/job ; rate = 1/6.96 job/min
-------
Chelsea DATA:
time = 15 min/job ; rate = 1/15 job/min
============
Elisa DATA:
time = x min/job ; rate = 1/x job/min
------------
Equation:
rate + rate = together rate
1/15 + 1/x = 1/6.96
(x+15)/15x = 1/6.96
Cross multiply to get:
6.96(x+15) = 15x
6.96x + 6.96*15 = 15x
8.04x = 6.96*15
x = 12.985 minutes (Elisa time to do the job alone)
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Cheers,
Stan H.
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