document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=238860>Question 238860</A>: <I><SPAN STYLE=\"word-break: break-all;\"> You drove 56 miles one way on a service call. On the return trip your average speed was 8 miles per hour faster and took 10 fewer minutes. What was the average speed on the return trip?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #175497 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=175497\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I write 2 equations, 1 for each trip<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5B1%5D+=+r%5B1%5D%2At%5B1%5D ALIGN=MIDDLE  ALT=\"d%5B1%5D+=+r%5B1%5D%2At%5B1%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5B2%5D+=+r%5B2%5D%2At%5B2%5D ALIGN=MIDDLE  ALT=\"d%5B2%5D+=+r%5B2%5D%2At%5B2%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "given:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5B1%5D+=+56 ALIGN=MIDDLE  ALT=\"d%5B1%5D+=+56\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5B2%5D+=+56 ALIGN=MIDDLE  ALT=\"d%5B2%5D+=+56\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B2%5D+=+r%5B1%5D+%2B+8 ALIGN=MIDDLE  ALT=\"r%5B2%5D+=+r%5B1%5D+%2B+8\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi/hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5B2%5D+=+t%5B1%5D+-+1%2F6 ALIGN=MIDDLE  ALT=\"t%5B2%5D+=+t%5B1%5D+-+1%2F6\"   DISABLED_style= \"max-width:90%; height:auto;\" > (10 min is 1/6 hr)<BR>\n" );
document.write( "------------------<BR>\n" );
document.write( "given:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5B1%5D+=+r%5B1%5D%2At%5B1%5D ALIGN=MIDDLE  ALT=\"d%5B1%5D+=+r%5B1%5D%2At%5B1%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+r%5B1%5D%2At%5B1%5D ALIGN=MIDDLE  ALT=\"56+=+r%5B1%5D%2At%5B1%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5B2%5D+=+r%5B2%5D%2At%5B2%5D ALIGN=MIDDLE  ALT=\"d%5B2%5D+=+r%5B2%5D%2At%5B2%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+%28r%5B1%5D+%2B+8%29%2A%28t%5B1%5D+-+1%2F6%29 ALIGN=MIDDLE  ALT=\"56+=+%28r%5B1%5D+%2B+8%29%2A%28t%5B1%5D+-+1%2F6%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "------------------<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+r%5B1%5D%2At%5B1%5D+%2B+8t%5B1%5D+-+%281%2F6%29%2Ar%5B1%5D+-+4%2F3 ALIGN=MIDDLE  ALT=\"56+=+r%5B1%5D%2At%5B1%5D+%2B+8t%5B1%5D+-+%281%2F6%29%2Ar%5B1%5D+-+4%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Substitute (1) in (2)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+56+%2B+8t%5B1%5D+-+%281%2F6%29%2Ar%5B1%5D+-+4%2F3 ALIGN=MIDDLE  ALT=\"56+=+56+%2B+8t%5B1%5D+-+%281%2F6%29%2Ar%5B1%5D+-+4%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Subtract <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56 ALIGN=MIDDLE  ALT=\"56\"   DISABLED_style= \"max-width:90%; height:auto;\" > from both sides<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=8t%5B1%5D+-+%281%2F6%29%2Ar%5B1%5D+=+4%2F3 ALIGN=MIDDLE  ALT=\"8t%5B1%5D+-+%281%2F6%29%2Ar%5B1%5D+=+4%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Multiply both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=6 ALIGN=MIDDLE  ALT=\"6\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=48t%5B1%5D+-+r%5B1%5D+=+8 ALIGN=MIDDLE  ALT=\"48t%5B1%5D+-+r%5B1%5D+=+8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and, from (1)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=48%2A56%2Fr%5B1%5D+-+r%5B1%5D+=+8 ALIGN=MIDDLE  ALT=\"48%2A56%2Fr%5B1%5D+-+r%5B1%5D+=+8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2688%2Fr%5B1%5D+-+r%5B1%5D+=+8 ALIGN=MIDDLE  ALT=\"2688%2Fr%5B1%5D+-+r%5B1%5D+=+8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Multiply both sides  by <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;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2688+-+%28r%5B1%5D%29%5E2+=+8r%5B1%5D ALIGN=MIDDLE  ALT=\"2688+-+%28r%5B1%5D%29%5E2+=+8r%5B1%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28r%5B1%5D%29%5E2+%2B+8r%5B1%5D+-+2688+=+0 ALIGN=MIDDLE  ALT=\"%28r%5B1%5D%29%5E2+%2B+8r%5B1%5D+-+2688+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Use quadratic equation<BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B1%5D+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"r%5B1%5D+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=a+=+1 ALIGN=MIDDLE  ALT=\"a+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=b+=+8 ALIGN=MIDDLE  ALT=\"b+=+8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=c+=+-2688 ALIGN=MIDDLE  ALT=\"c+=+-2688\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B1%5D+=+%28-8+%2B-+sqrt%28+8%5E2-4%2A1%2A%28-2688%29+%29%29%2F%282%2A1%29+ ALIGN=MIDDLE  ALT=\"r%5B1%5D+=+%28-8+%2B-+sqrt%28+8%5E2-4%2A1%2A%28-2688%29+%29%29%2F%282%2A1%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B1%5D+=+%28-8+%2B-+sqrt%28+64+%2B+10752+%29%29%2F2+ ALIGN=MIDDLE  ALT=\"r%5B1%5D+=+%28-8+%2B-+sqrt%28+64+%2B+10752+%29%29%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B1%5D+=+%28-8+%2B-+sqrt%28+10816+%29%29%2F2+ ALIGN=MIDDLE  ALT=\"r%5B1%5D+=+%28-8+%2B-+sqrt%28+10816+%29%29%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B1%5D+=+%28-8+%2B+104%29%2F2 ALIGN=MIDDLE  ALT=\"r%5B1%5D+=+%28-8+%2B+104%29%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B1%5D+=+96%2F2 ALIGN=MIDDLE  ALT=\"r%5B1%5D+=+96%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B1%5D+=+48 ALIGN=MIDDLE  ALT=\"r%5B1%5D+=+48\"   DISABLED_style= \"max-width:90%; height:auto;\" > (the negative answer is impossible)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5B2%5D+=+r%5B1%5D+%2B+8 ALIGN=MIDDLE  ALT=\"r%5B2%5D+=+r%5B1%5D+%2B+8\"   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+=+48+%2B+8 ALIGN=MIDDLE  ALT=\"r%5B2%5D+=+48+%2B+8\"   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=+56 ALIGN=MIDDLE  ALT=\"r%5B2%5D=+56\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The speed on the return trip is 56 mi/hr<BR>\n" );
document.write( "check answer:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+r%5B1%5D%2At%5B1%5D ALIGN=MIDDLE  ALT=\"56+=+r%5B1%5D%2At%5B1%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+%28r%5B1%5D+%2B+8%29%2A%28t%5B1%5D+-+1%2F6%29 ALIGN=MIDDLE  ALT=\"56+=+%28r%5B1%5D+%2B+8%29%2A%28t%5B1%5D+-+1%2F6%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-----------------------<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+48%2At%5B1%5D ALIGN=MIDDLE  ALT=\"56+=+48%2At%5B1%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5B1%5D+=+1.167 ALIGN=MIDDLE  ALT=\"t%5B1%5D+=+1.167\"   DISABLED_style= \"max-width:90%; height:auto;\" > hr (1 hr 10 min)<BR>\n" );
document.write( "and<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+%2848+%2B+8%29%2A%28t%5B1%5D+-+1%2F6%29 ALIGN=MIDDLE  ALT=\"56+=+%2848+%2B+8%29%2A%28t%5B1%5D+-+1%2F6%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=56+=+56%2A%28t%5B1%5D+-+1%2F6%29 ALIGN=MIDDLE  ALT=\"56+=+56%2A%28t%5B1%5D+-+1%2F6%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1+=+t%5B1%5D+-+1%2F6 ALIGN=MIDDLE  ALT=\"1+=+t%5B1%5D+-+1%2F6\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=6+=+6t%5B1%5D+-+1 ALIGN=MIDDLE  ALT=\"6+=+6t%5B1%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=6t%5B1%5D+=+7 ALIGN=MIDDLE  ALT=\"6t%5B1%5D+=+7\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5B1%5D+=+1.167 ALIGN=MIDDLE  ALT=\"t%5B1%5D+=+1.167\"   DISABLED_style= \"max-width:90%; height:auto;\" > hr<BR>\n" );
document.write( "OK\r<BR>\n" );
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document.write( "  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );