document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1111066>Question 1111066</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A train leaves a station at 11am, heading north. Another train, 320 km away, leaves at the same time, heading south. The average speed of the train heading north is 20 km/hr faster than that of the train heading south. If the trains pass each other at 1.30 pm, what was the average speed of the southbound train? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #726079 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=726079\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 11 AM to 1:30 PM is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2.5+ ALIGN=MIDDLE  ALT=\"+2.5+\"   DISABLED_style= \"max-width:90%; height:auto;\" > hrs<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+ ALIGN=MIDDLE  ALT=\"+s+\"   DISABLED_style= \"max-width:90%; height:auto;\" > km/hr = the speed of the southbound train<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+%2B+20+ ALIGN=MIDDLE  ALT=\"+s+%2B+20+\"   DISABLED_style= \"max-width:90%; height:auto;\" > km/hr is the speed of the nothbound train<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;\" > km = distance traveled by southbound train<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+320+-+d+ ALIGN=MIDDLE  ALT=\"+320+-+d+\"   DISABLED_style= \"max-width:90%; height:auto;\" > km = distance traveled by northbound train<BR>\n" );
document.write( "---------------------------------------------------<BR>\n" );
document.write( "Equation for the southbound train:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d+=+s%2A2.5+ ALIGN=MIDDLE  ALT=\"+d+=+s%2A2.5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Equation for nothbound train:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+320+-+d+=+%28+s+%2B+20+%29%2A2.5+ ALIGN=MIDDLE  ALT=\"+320+-+d+=+%28+s+%2B+20+%29%2A2.5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------------------------<BR>\n" );
document.write( "Plug (1) into (2)<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+320+-+2.5s+=+%28+s+%2B+20+%29%2A2.5+ ALIGN=MIDDLE  ALT=\"+320+-+2.5s+=+%28+s+%2B+20+%29%2A2.5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+320+-+2.5s+=+2.5s+%2B+50+ ALIGN=MIDDLE  ALT=\"+320+-+2.5s+=+2.5s+%2B+50+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+5s+=+320+-+50+ ALIGN=MIDDLE  ALT=\"+5s+=+320+-+50+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+5s+=+270+ ALIGN=MIDDLE  ALT=\"+5s+=+270+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+54+ ALIGN=MIDDLE  ALT=\"+s+=+54+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The average speed of the southbound train <BR>\n" );
document.write( "is 54 km/hr<BR>\n" );
document.write( "-------------------<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d+=+54%2A2.5+ ALIGN=MIDDLE  ALT=\"+d+=+54%2A2.5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d+=+135+ ALIGN=MIDDLE  ALT=\"+d+=+135+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+320+-+2.5%2A54+=+%28+54+%2B+20+%29%2A2.5+ ALIGN=MIDDLE  ALT=\"+320+-+2.5%2A54+=+%28+54+%2B+20+%29%2A2.5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+320+-+135+=+74%2A2.5+ ALIGN=MIDDLE  ALT=\"+320+-+135+=+74%2A2.5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+185+=+185+ ALIGN=MIDDLE  ALT=\"+185+=+185+\"   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=+135+%2B+185+=+320+ ALIGN=MIDDLE  ALT=\"+135+%2B+185+=+320+\"   DISABLED_style= \"max-width:90%; height:auto;\" > km<BR>\n" );
document.write( "OK\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );