document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1094371>Question 1094371</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Traveling at full speed on a river, it takes 4 hours for a motorboat to travel 18 miles upstream and 21 miles downstream.  If the current's speed is 2 mph, what is the maximum 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 #708928 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39620)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=708928\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Travel Rates Rule, RT=D to relate speed, time, distance\r<BR>\n" );
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document.write( "r, speed of boat when not in a current\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r-2 ALIGN=MIDDLE  ALT=\"r-2\"   DISABLED_style= \"max-width:90%; height:auto;\" >, upstream rate<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%2B2 ALIGN=MIDDLE  ALT=\"r%2B2\"   DISABLED_style= \"max-width:90%; height:auto;\" >, downstream rate\r<BR>\n" );
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document.write( "total time, 4 hours\r<BR>\n" );
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document.write( "               SPEED       TIME       DISTANCE\r\n" );
document.write( "UPSTREAM        r-2       18/(r-2)      18\r\n" );
document.write( "DOWNSTREAM      r+2       21/(r+2)      21\r\n" );
document.write( "TOTAL                      4\r\n" );
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document.write( "Total time:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=18%2F%28r-2%29%2B21%2F%28r%2B2%29=4 ALIGN=MIDDLE  ALT=\"18%2F%28r-2%29%2B21%2F%28r%2B2%29=4\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4r%5E2-39r-10=0 ALIGN=MIDDLE  ALT=\"4r%5E2-39r-10=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=discriminant=39%5E2%2B4%2A4%2A10=1681=41%5E2 ALIGN=MIDDLE  ALT=\"discriminant=39%5E2%2B4%2A4%2A10=1681=41%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r=%2839%2B-+41%29%2F8 ALIGN=MIDDLE  ALT=\"r=%2839%2B-+41%29%2F8\"   DISABLED_style= \"max-width:90%; height:auto;\" >-----<i>must take the positive value</i>\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r=80%2F8 ALIGN=MIDDLE  ALT=\"r=80%2F8\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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