document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=106198>Question 106198</A>: <I><SPAN STYLE=\"word-break: break-all;\"> On a river a boat travels 240 miles downstream in the same amount of time that it takes to travel 160 miles upstream.  The speed of the boat without current is 25 mph.  Find the speed of the river.  Be sure to define your variable, write an equation, and show how you solved it. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #77327 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=77327\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> On a river a boat travels 240 miles downstream in the same amount of time that it takes to travel 160 miles upstream. The speed of the boat without current is 25 mph. Find the speed of the river.<BR>\n" );
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document.write( "Let x = speed of the river<BR>\n" );
document.write( "Then<BR>\n" );
document.write( "(25-x) = speed upstream<BR>\n" );
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document.write( "(25+x) = speed downstream<BR>\n" );
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document.write( "It tells us the times are equal, make a simple time equation from this fact:<BR>\n" );
document.write( "Time = distance/speed<BR>\n" );
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document.write( "Time up = time down<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=160%2F%28%2825-x%29%29 ALIGN=MIDDLE  ALT=\"160%2F%28%2825-x%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=240%2F%28%2825%2Bx%29%29 ALIGN=MIDDLE  ALT=\"240%2F%28%2825%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "Cross multiply and you have:<BR>\n" );
document.write( "160(25+x) = 240(25-x)<BR>\n" );
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document.write( "4000 + 160x = 6000 - 240x<BR>\n" );
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document.write( "160x + 240x = 6000 - 4000<BR>\n" );
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document.write( "400x = 2000<BR>\n" );
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document.write( "x = 2000/400<BR>\n" );
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document.write( "x = 5 mph is the current:<BR>\n" );
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document.write( "Check solution by seeing if, indeed, the times are the same:<BR>\n" );
document.write( "Upstream: 160/20 = 8 hrs<BR>\n" );
document.write( "Downstream: 240/30 = 8 hrs, confirms our solution<BR>\n" );
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document.write( "Make sense to you? Any questions?\r<BR>\n" );
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document.write( " </SPAN>\n" );
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