document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=884300>Question 884300</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Joe and Louis are making a drive from San Diego to Salt Lake City.  After 4 hours of driving, they are 507 miles from Salt Lake City.  Eight hours into their trip, they are only 267 miles away from their destination.  Assume they averaged the same speed for the entire trip.\r<BR>\n" );
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document.write( "To write the expression, define a variable for the time they have been driving and use this variable to write an expression for the distance they are from Salt Lake City.\r<BR>\n" );
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document.write( "I need an expression for y = mx = b </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #534161 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=534161\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+y+=+m%2Ax+%2B+b+ ALIGN=MIDDLE  ALT=\"+y+=+m%2Ax+%2B+b+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The slope will be their average speed, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+ ALIGN=MIDDLE  ALT=\"+s+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d+ ALIGN=MIDDLE  ALT=\"+d+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the distance from Salt Lake City<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d%5B1%5D+ ALIGN=MIDDLE  ALT=\"+d%5B1%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the distance they have already traveled<BR>\n" );
document.write( "The equation looks like:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d+=+s%2At+%2B+d%5B1%5D+ ALIGN=MIDDLE  ALT=\"+d+=+s%2At+%2B+d%5B1%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" >   <BR>\n" );
document.write( "Set <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+0+ ALIGN=MIDDLE  ALT=\"+t+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" > to find <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d%5B1%5D+ ALIGN=MIDDLE  ALT=\"+d%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%5B1%5D+=+507++ ALIGN=MIDDLE  ALT=\"+d%5B1%5D+=+507++\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------------<BR>\n" );
document.write( "Between 8 hrs and 4 hrs of driving, they have been<BR>\n" );
document.write( "driving 4 hrs and have traveled <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+507+-+267+=+240+ ALIGN=MIDDLE  ALT=\"+507+-+267+=+240+\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+240%2F4+ ALIGN=MIDDLE  ALT=\"+s+=+240%2F4+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+60+ ALIGN=MIDDLE  ALT=\"+s+=+60+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "------------<BR>\n" );
document.write( "I come up with:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d+=+-60t+%2B+507+ ALIGN=MIDDLE  ALT=\"+d+=+-60t+%2B+507+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------------<BR>\n" );
document.write( "I made the slope negative because <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d+ ALIGN=MIDDLE  ALT=\"+d+\"   DISABLED_style= \"max-width:90%; height:auto;\" > has to get smaller<BR>\n" );
document.write( "as <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+ ALIGN=MIDDLE  ALT=\"+t+\"   DISABLED_style= \"max-width:90%; height:auto;\" > increases<BR>\n" );
document.write( "Here's a plot:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+graph%28+400%2C+400%2C+-1%2C+10%2C+-50%2C+600%2C+-60x+%2B+507+%29+ ALIGN=MIDDLE  ALT=\"+graph%28+400%2C+400%2C+-1%2C+10%2C+-50%2C+600%2C+-60x+%2B+507+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "It looks like they get to Salt Lake City about 8.5 hrs since they <BR>\n" );
document.write( "were 507 miles away ( at <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t=0+ ALIGN=MIDDLE  ALT=\"+t=0+\"   DISABLED_style= \"max-width:90%; height:auto;\" > )<BR>\n" );
document.write( "Hope this helps\r<BR>\n" );
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