document.write( "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? \n" ); document.write( "

Algebra.Com's Answer #454009 by stanbon(75887) $\"\"$ $\"About$

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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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\n" ); document.write( "Let \"f\" be the father's rate and \"s\" the son's rate.
\n" ); document.write( "Equations:
\n" ); document.write( "6f + 12s = 1 job
\n" ); document.write( "9f + 8s = 1 job
\n" ); document.write( "---------------------------
\n" ); document.write( "Multiply top equation by 9
\n" ); document.write( "Multiply bottom equation by 6
\n" ); document.write( "------
\n" ); document.write( "54f + 108s = 9
\n" ); document.write( "54f + 48s = 6
\n" ); document.write( "----
\n" ); document.write( "Subtract and solve for \"s\"
\n" ); document.write( "60s = 3
\n" ); document.write( "s = 1/20 job/hr
\n" ); document.write( "son's time = 20 hrs/job
\n" ); document.write( "-----------------------------
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
\n" ); document.write( " \n" ); document.write( "

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