document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=745794>Question 745794</A>: <I><SPAN STYLE=\"word-break: break-all;\">  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? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #454007 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=454007\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> You can add their rates of digging to get their rate <BR>\n" );
document.write( "working together<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B1%5D+ ALIGN=MIDDLE  ALT=\"+R%5B1%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = father's rate of digging<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B2%5D+ ALIGN=MIDDLE  ALT=\"+R%5B2%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = Son's rate of digging<BR>\n" );
document.write( "--------------------------------<BR>\n" );
document.write( "In general, I can say that:<BR>\n" );
document.write( "( time spent digging ) x ( rate of digging ) = fraction of job done<BR>\n" );
document.write( "---------------<BR>\n" );
document.write( "given:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+6R%5B1%5D+%2B+12R%5B2%5D+=+1+ ALIGN=MIDDLE  ALT=\"+6R%5B1%5D+%2B+12R%5B2%5D+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+9R%5B1%5D+%2B+8R%5B2%5D+=+1+ ALIGN=MIDDLE  ALT=\"+9R%5B1%5D+%2B+8R%5B2%5D+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "( note that <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+1+ ALIGN=MIDDLE  ALT=\"+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" > means entire job done )<BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "Multiply both sides of (1) by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3+ ALIGN=MIDDLE  ALT=\"+3+\"   DISABLED_style= \"max-width:90%; height:auto;\" > and<BR>\n" );
document.write( "both sides of (2) by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2+ ALIGN=MIDDLE  ALT=\"+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Then subtract (2) from (1)<BR>\n" );
document.write( "----------------------<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+18R%5B1%5D+%2B+36R%5B2%5D+=+3+ ALIGN=MIDDLE  ALT=\"+18R%5B1%5D+%2B+36R%5B2%5D+=+3+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-18R%5B1%5D+-+16R%5B2%5D+=+-2++ ALIGN=MIDDLE  ALT=\"+-18R%5B1%5D+-+16R%5B2%5D+=+-2++\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+20R%5B2%5D+=+1+ ALIGN=MIDDLE  ALT=\"+20R%5B2%5D+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B2%5D+=+1%2F20+ ALIGN=MIDDLE  ALT=\"+R%5B2%5D+=+1%2F20+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-----------------<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+6R%5B1%5D+%2B+12R%5B2%5D+=+1+ ALIGN=MIDDLE  ALT=\"+6R%5B1%5D+%2B+12R%5B2%5D+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B1%5D+%2B+2R%5B2%5D+=+1%2F6+ ALIGN=MIDDLE  ALT=\"+R%5B1%5D+%2B+2R%5B2%5D+=+1%2F6+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B1%5D+%2B+2R%5B2%5D+=+1%2F6+ ALIGN=MIDDLE  ALT=\"+R%5B1%5D+%2B+2R%5B2%5D+=+1%2F6+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B1%5D+%2B+2%2A%281%2F20%29+=+1%2F6+ ALIGN=MIDDLE  ALT=\"+R%5B1%5D+%2B+2%2A%281%2F20%29+=+1%2F6+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B1%5D+=+1%2F6+-+1%2F10+ ALIGN=MIDDLE  ALT=\"+R%5B1%5D+=+1%2F6+-+1%2F10+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B1%5D+=+5%2F30+-+3%2F30+ ALIGN=MIDDLE  ALT=\"+R%5B1%5D+=+5%2F30+-+3%2F30+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B1%5D+=+2%2F30+ ALIGN=MIDDLE  ALT=\"+R%5B1%5D+=+2%2F30+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5B1%5D+=+1%2F15+ ALIGN=MIDDLE  ALT=\"+R%5B1%5D+=+1%2F15+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-----------------<BR>\n" );
document.write( "The son would take 20 hrs working alone<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+9R%5B1%5D+%2B+8R%5B2%5D+=+1+ ALIGN=MIDDLE  ALT=\"+9R%5B1%5D+%2B+8R%5B2%5D+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+9%2A%281%2F15%29+%2B+8%2A%281%2F20%29+=+1+ ALIGN=MIDDLE  ALT=\"+9%2A%281%2F15%29+%2B+8%2A%281%2F20%29+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+9%2F15+%2B+8%2F20+=+1+ ALIGN=MIDDLE  ALT=\"+9%2F15+%2B+8%2F20+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+36%2F60+%2B+24%2F60+=+60%2F60+ ALIGN=MIDDLE  ALT=\"+36%2F60+%2B+24%2F60+=+60%2F60+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+1+=+1+ ALIGN=MIDDLE  ALT=\"+1+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK\r<BR>\n" );
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document.write( " </SPAN>\n" );
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