document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=40857>Question 40857</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A motorboat goes 5 miles upstream in the same time it requires to go 7 miles downstream.  If the river flows at 2 mph, find the speed of the boat 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 #26264 by </B><A HREF=/tutors/aboutme.mpl?userid=longjonsilver><B>longjonsilver(2297)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=longjonsilver><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=longjonsilver><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=26264\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> let speed of boat in still water be x mph\r<BR>\n" );
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document.write( "speed upstream = x-2<BR>\n" );
document.write( "speed downstream = x+2\r<BR>\n" );
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document.write( "speed = distance/time\r<BR>\n" );
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document.write( "So, x-2 = 5/t<BR>\n" );
document.write( "and x+2 = 7/t\r<BR>\n" );
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document.write( "The time in both journeys is the same, so i have them both as \"t\". We get:\r<BR>\n" );
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document.write( "t = 5/(x-2) = 7/(x+2)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+5%2F%28x-2%29+=+7%2F%28x%2B2%29+ ALIGN=MIDDLE  ALT=\"+5%2F%28x-2%29+=+7%2F%28x%2B2%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%28x%2B2%29+=+7%28x-2%29+ ALIGN=MIDDLE  ALT=\"+5%28x%2B2%29+=+7%28x-2%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+5x%2B10+=+7x-14+ ALIGN=MIDDLE  ALT=\"+5x%2B10+=+7x-14+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+10+=+2x-14+ ALIGN=MIDDLE  ALT=\"+10+=+2x-14+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+24+=+2x+ ALIGN=MIDDLE  ALT=\"+24+=+2x+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--> x = 24/2<BR>\n" );
document.write( "so x = 12 mph\r<BR>\n" );
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document.write( "Check:<BR>\n" );
document.write( "upstream: speed is 10mph. 5 miles takes 2 hours<BR>\n" );
document.write( "downstream: speed is 14mph. 7 miles takes 2 hours too.\r<BR>\n" );
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document.write( "jon </SPAN>\n" );
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