document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1194505>Question 1194505</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A sailboat can travel 60 miles upstream in the same time it takes to travel 100 miles downstream. If the speed of the boat in still water is 20 miles per hour, what is the speed of 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 #826717 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39617)</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=826717\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <PRE STYLE=\"white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;\">\r\n" );
document.write( "              SPEED           TIME          DIST.\r\n" );
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document.write( "UPSTR         20-c             t              60\r\n" );
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document.write( "DOWNSTR       20+c             t             100\r\n" );
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document.write( "Value of <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t ALIGN=MIDDLE  ALT=\"t\"   DISABLED_style= \"max-width:90%; height:auto;\" > is equal both to <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=60%2F%2820-c%29 ALIGN=MIDDLE  ALT=\"60%2F%2820-c%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > and to <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%2F%2820%2Bc%29 ALIGN=MIDDLE  ALT=\"100%2F%2820%2Bc%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >, so meaning <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight_green%2860%2F%2820-c%29=100%2F%2820%2Bc%29%29 ALIGN=MIDDLE  ALT=\"highlight_green%2860%2F%2820-c%29=100%2F%2820%2Bc%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r<BR>\n" );
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document.write( "Simplify and solve for c.\r<BR>\n" );
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document.write( "Same type exercise comes up too often.<BR>\n" );
document.write( "Something moves upstream for U distance in the same time as it moves D distance downstream.  The craft or vehicle normally moves at R speed in absence of stream or river current.<BR>\n" );
document.write( "What is the speed of the current?\r<BR>\n" );
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document.write( "              SPEED           TIME          DIST.\r\n" );
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document.write( "UPSTR         R-c             U/(R-c)         U\r\n" );
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document.write( "DOWNSTR       R+c             D/(R+c)         D\r\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=U%2F%28R-c%29=D%2F%28R%2Bc%29 ALIGN=MIDDLE  ALT=\"U%2F%28R-c%29=D%2F%28R%2Bc%29\"   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=U%28R%2Bc%29=D%28R-c%29 ALIGN=MIDDLE  ALT=\"U%28R%2Bc%29=D%28R-c%29\"   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=UR%2BUc=DR-Dc ALIGN=MIDDLE  ALT=\"UR%2BUc=DR-Dc\"   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=Uc%2BDc=DR-UR ALIGN=MIDDLE  ALT=\"Uc%2BDc=DR-UR\"   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=%28U%2BD%29c=R%28D-U%29 ALIGN=MIDDLE  ALT=\"%28U%2BD%29c=R%28D-U%29\"   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=highlight_green%28c=R%28%28D-U%29%2F%28D%2BU%29%29%29 ALIGN=MIDDLE  ALT=\"highlight_green%28c=R%28%28D-U%29%2F%28D%2BU%29%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
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