Question 745794
father and a his son can dig a well if the father works 6 hours and his son works 12 hours or they can do its if the father works 9 hours and the son works 8 hours. How long will it take for the son to dig the well alone?
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Let "f" be the father's rate and "s" the son's rate.
Equations:
6f + 12s = 1 job
9f + 8s = 1 job
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Multiply top equation by 9
Multiply bottom equation by 6
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54f + 108s = 9
54f + 48s = 6
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Subtract and solve for "s"
60s = 3
s = 1/20 job/hr
son's time = 20 hrs/job
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Cheers,
Stan H.