document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=736018>Question 736018</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am a librarian. A patron needs a solution to this problem:\r<BR>\n" );
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document.write( "The speed of a boat in still waters is 10 km/h<BR>\n" );
document.write( "The boat travels 12 km upstream and 28 km downstream in a total of 4 hours.<BR>\n" );
document.write( "What is the speed of the stream?\r<BR>\n" );
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document.write( "Thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #449635 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=449635\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> let speed of current be c kph\r<BR>\n" );
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document.write( "upstream speed = 10-c<BR>\n" );
document.write( "upstream distance = 12 \r<BR>\n" );
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document.write( "down stream speed = 10+c<BR>\n" );
document.write( "down stream distance = 28 km\r<BR>\n" );
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document.write( "upstream time + downstream time = 4\r<BR>\n" );
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document.write( "t=d/r\r<BR>\n" );
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document.write( "12/(10-c) + 28/(10+c)= 4\r<BR>\n" );
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document.write( "multiply the equation by (10+c)(10-c)\r<BR>\n" );
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document.write( "12(10+c)+28(10-c)=4(10+c)(10-c)\r<BR>\n" );
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document.write( "120+12c+280-28c=4(100-c^2)\r<BR>\n" );
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document.write( "400-16c=400-4c^2\r<BR>\n" );
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document.write( "re arrange<BR>\n" );
document.write( "4c^2=16c\r<BR>\n" );
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document.write( "/4c<BR>\n" );
document.write( "c=4\r<BR>\n" );
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document.write( "current speed = 4 kph </SPAN>\n" );
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