document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=269091>Question 269091</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Train A leaves a station traveling at 40 miles per hour. Four hours later train B leaves the same station traveling in the same direction at 60 miles per hour. How long does it take for train B to catch up to train A? \r<BR>\n" );
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document.write( "[A] 9 hr [B]10hr [C] 8hr [D] 11hr </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #197232 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=197232\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> What is A's headstart?<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+r%2At ALIGN=MIDDLE  ALT=\"d+=+r%2At\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+40%2A4 ALIGN=MIDDLE  ALT=\"d+=+40%2A4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+160 ALIGN=MIDDLE  ALT=\"d+=+160\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi<BR>\n" );
document.write( "Now you start a stopwatch. The start time and stop time<BR>\n" );
document.write( "for both trains will be the same, or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5Ba%5D+=+t%5Bb%5D ALIGN=MIDDLE  ALT=\"t%5Ba%5D+=+t%5Bb%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "so call this time <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t ALIGN=MIDDLE  ALT=\"t\"   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%5Ba%5D+=+r%5Ba%5D%2At ALIGN=MIDDLE  ALT=\"d%5Ba%5D+=+r%5Ba%5D%2At\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Bb%5D+=+r%5Bb%5D%2At ALIGN=MIDDLE  ALT=\"d%5Bb%5D+=+r%5Bb%5D%2At\"   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=r%5Ba%5D+=+40 ALIGN=MIDDLE  ALT=\"r%5Ba%5D+=+40\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5Bb%5D+=+60 ALIGN=MIDDLE  ALT=\"r%5Bb%5D+=+60\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "So, now I have:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Ba%5D+=+40t ALIGN=MIDDLE  ALT=\"d%5Ba%5D+=+40t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Bb%5D+=+60t ALIGN=MIDDLE  ALT=\"d%5Bb%5D+=+60t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Train B has to make up the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=160 ALIGN=MIDDLE  ALT=\"160\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi headstart of train A, so<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Bb%5D+=+d%5Ba%5D+%2B+160 ALIGN=MIDDLE  ALT=\"d%5Bb%5D+=+d%5Ba%5D+%2B+160\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "So,  I have:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Ba%5D+=+40t ALIGN=MIDDLE  ALT=\"d%5Ba%5D+=+40t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Ba%5D+%2B+160+=+60t ALIGN=MIDDLE  ALT=\"d%5Ba%5D+%2B+160+=+60t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Substitute (1) into (2)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=40t+%2B+160+=+60t ALIGN=MIDDLE  ALT=\"40t+%2B+160+=+60t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=20t+=+160 ALIGN=MIDDLE  ALT=\"20t+=+160\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t+=+8 ALIGN=MIDDLE  ALT=\"t+=+8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "It takes 8 hrs for B to catch A<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Ba%5D+=+40t ALIGN=MIDDLE  ALT=\"d%5Ba%5D+=+40t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Ba%5D+=+40%2A8 ALIGN=MIDDLE  ALT=\"d%5Ba%5D+=+40%2A8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Ba%5D+=+320 ALIGN=MIDDLE  ALT=\"d%5Ba%5D+=+320\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Bb%5D+=+60t ALIGN=MIDDLE  ALT=\"d%5Bb%5D+=+60t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Bb%5D+=+60%2A8 ALIGN=MIDDLE  ALT=\"d%5Bb%5D+=+60%2A8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Bb%5D+=+480 ALIGN=MIDDLE  ALT=\"d%5Bb%5D+=+480\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%5Bb%5D+-+d%5Ba%5D+=+480+-+320 ALIGN=MIDDLE  ALT=\"d%5Bb%5D+-+d%5Ba%5D+=+480+-+320\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=480+-+320+=+160 ALIGN=MIDDLE  ALT=\"480+-+320+=+160\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "That was headstart of A\r<BR>\n" );
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document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );