document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=172553>Question 172553</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the 4-mph current, it took her 20 minutes longer to get their than to return. How fast will her boat go in still water?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #127465 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=127465\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 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;\" >= her speed in still water<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=c ALIGN=MIDDLE  ALT=\"c\"   DISABLED_style= \"max-width:90%; height:auto;\" >= the speed of the current<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 she has to go<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5Bu%5D ALIGN=MIDDLE  ALT=\"t%5Bu%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" >= time going upstream in hrs<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5Bd%5D ALIGN=MIDDLE  ALT=\"t%5Bd%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" >= time going downstream in hrs<BR>\n" );
document.write( "Then<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+-+c ALIGN=MIDDLE  ALT=\"s+-+c\"   DISABLED_style= \"max-width:90%; height:auto;\" >= speed of boat going upstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+%2B+c ALIGN=MIDDLE  ALT=\"s+%2B+c\"   DISABLED_style= \"max-width:90%; height:auto;\" >= speed of boat going downstream<BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "The problem says<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=c+=+4 ALIGN=MIDDLE  ALT=\"c+=+4\"   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%5Bu%5D+=+t%5Bd%5D+%2B+%281%2F3%29 ALIGN=MIDDLE  ALT=\"t%5Bu%5D+=+t%5Bd%5D+%2B+%281%2F3%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+5 ALIGN=MIDDLE  ALT=\"d+=+5\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi<BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+%28s+-+c%29%2At%5Bu%5D ALIGN=MIDDLE  ALT=\"d+=+%28s+-+c%29%2At%5Bu%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" > going upstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+%28s+-+4%29%2A%28t%5Bd%5D+%2B+%281%2F3%29%29 ALIGN=MIDDLE  ALT=\"5+=+%28s+-+4%29%2A%28t%5Bd%5D+%2B+%281%2F3%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+t%5Bd%5D%2As+-+4t%5Bd%5D+%2B+%281%2F3%29%2As+-+%284%2F3%29 ALIGN=MIDDLE  ALT=\"5+=+t%5Bd%5D%2As+-+4t%5Bd%5D+%2B+%281%2F3%29%2As+-+%284%2F3%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and, going downstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+%28s+%2B+4%29%2At%5Bd%5D ALIGN=MIDDLE  ALT=\"5+=+%28s+%2B+4%29%2At%5Bd%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%5Bd%5D+=+5+%2F+%28s+%2B+4%29 ALIGN=MIDDLE  ALT=\"t%5Bd%5D+=+5+%2F+%28s+%2B+4%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Substitute this into the upstream equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+%285%2F%28s+%2B+4%29%29%2As+-+4%2A5+%2F+%28s+%2B+4%29+%2B+%281%2F3%29%2As+-+4%2F3 ALIGN=MIDDLE  ALT=\"5+=+%285%2F%28s+%2B+4%29%29%2As+-+4%2A5+%2F+%28s+%2B+4%29+%2B+%281%2F3%29%2As+-+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=3%2A%28s+%2B+4%29 ALIGN=MIDDLE  ALT=\"3%2A%28s+%2B+4%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15%2A%28s+%2B+4%29+=+15s+-+60+%2B+s%2A%28s+%2B+4%29+-+4%2A%28s+%2B+4%29 ALIGN=MIDDLE  ALT=\"15%2A%28s+%2B+4%29+=+15s+-+60+%2B+s%2A%28s+%2B+4%29+-+4%2A%28s+%2B+4%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15s+%2B+60+=+15s+-+60+%2B+s%5E2+%2B+4s+-+4s+-+16 ALIGN=MIDDLE  ALT=\"15s+%2B+60+=+15s+-+60+%2B+s%5E2+%2B+4s+-+4s+-+16\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s%5E2+-+120+-+16+=+0 ALIGN=MIDDLE  ALT=\"s%5E2+-+120+-+16+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s%5E2+-+136+=+0 ALIGN=MIDDLE  ALT=\"s%5E2+-+136+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s%5E2+=+136 ALIGN=MIDDLE  ALT=\"s%5E2+=+136\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+11.662 ALIGN=MIDDLE  ALT=\"s+=+11.662\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi/hr<BR>\n" );
document.write( "The speed of the boat in still water is 11.662 mi/hr<BR>\n" );
document.write( "check answer:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+-+c+=+s+-+4 ALIGN=MIDDLE  ALT=\"s+-+c+=+s+-+4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+-+4+=+7.662 ALIGN=MIDDLE  ALT=\"s+-+4+=+7.662\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+%2B+c+=+s+%2B+4 ALIGN=MIDDLE  ALT=\"s+%2B+c+=+s+%2B+4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+%2B+4+=+15.662 ALIGN=MIDDLE  ALT=\"s+%2B+4+=+15.662\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5Bd%5D+=+5+%2F+%28s+%2B+4%29 ALIGN=MIDDLE  ALT=\"t%5Bd%5D+=+5+%2F+%28s+%2B+4%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5Bd%5D+=+5+%2F+15.662 ALIGN=MIDDLE  ALT=\"t%5Bd%5D+=+5+%2F+15.662\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5Bd%5D+=+.319 ALIGN=MIDDLE  ALT=\"t%5Bd%5D+=+.319\"   DISABLED_style= \"max-width:90%; height:auto;\" >hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5Bu%5D+=+t%5Bd%5D+%2B+%281%2F3%29 ALIGN=MIDDLE  ALT=\"t%5Bu%5D+=+t%5Bd%5D+%2B+%281%2F3%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5Bu%5D+=+.6525 ALIGN=MIDDLE  ALT=\"t%5Bu%5D+=+.6525\"   DISABLED_style= \"max-width:90%; height:auto;\" >hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+%28s+-+c%29%2At%5Bu%5D ALIGN=MIDDLE  ALT=\"d+=+%28s+-+c%29%2At%5Bu%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" > going upstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+7.662%2A.6525 ALIGN=MIDDLE  ALT=\"5+=+7.662%2A.6525\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+4.9998 ALIGN=MIDDLE  ALT=\"5+=+4.9998\"   DISABLED_style= \"max-width:90%; height:auto;\" > close enough<BR>\n" );
document.write( "also<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+%28s+%2B+c%29%2At%5Bd%5D ALIGN=MIDDLE  ALT=\"d+=+%28s+%2B+c%29%2At%5Bd%5D\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+15.662%2A.319 ALIGN=MIDDLE  ALT=\"5+=+15.662%2A.319\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+4.996 ALIGN=MIDDLE  ALT=\"5+=+4.996\"   DISABLED_style= \"max-width:90%; height:auto;\" > close enough<BR>\n" );
document.write( "  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );