document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=250597>Question 250597</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A boat can go 33 mph in still water. It takes as long to go 300 miles upstream as it does to go downstream 360 miles. how fast is the current? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #182477 by </B><A HREF=/tutors/aboutme.mpl?userid=solver91311><B>solver91311(24713)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=solver91311><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=solver91311><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=182477\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font face=\"Garamond\" size=\"+2\">\r<BR>\n" );
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document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\Large r_c\"> represent the rate of the current.\r<BR>\n" );
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document.write( "When the boat is going upstream, against the current, it is going 33 mph through the water, but <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\Large 33\ -\ r_c\"> mph with respect to the riverbed or the bank of the river or whatever fixed thing you are using to measure the distance traveled against.  Likewise, when the boat is going downstream, it is travelling <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\Large 33\ +\ r_c\"> mph with respect to the riverbed.\r<BR>\n" );
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document.write( "Remember that distance equals rate times time, or <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\Large d\ =\ rt\">.  Solving this equation time in terms of distance and rate yields:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ t\ =\ \frac{d}{r}\">\r<BR>\n" );
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document.write( "Now let's substitute some values from the problem.  To describe the upstream trip:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ t\ =\ \frac{300}{33\ -\ r_c}\">\r<BR>\n" );
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document.write( "And for the downstream trip:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ t\ =\ \frac{360}{33\ +\ r_c}\">\r<BR>\n" );
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document.write( "But since we know that the time for each of the trips was the same (\"It takes as long...\"), we can now write:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ \frac{300}{33\ -\ r_c}\ =\ \frac{360}{33\ +\ r_c}\">\r<BR>\n" );
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document.write( "Now all you have to do is cross-multiply the proportion and solve for <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\Large r_c\">.\r<BR>\n" );
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document.write( "John<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE e^{i\pi} + 1 = 0\"><BR>\n" );
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