document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=310467>Question 310467</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The speed of the current in the Yankaton River is 3 kilometers per hour. If a boat travels 18 kilometers downstream in this river and then returns to its starting point all in 4 1/2 hours, what is the rate 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 #221973 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=221973\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  the speed of the boat in still water be x km/hr.\r<BR>\n" );
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document.write( "Downstream<BR>\n" );
document.write( "the speed will be x+3 km/hr.<BR>\n" );
document.write( "Distance traveled is 18 km.<BR>\n" );
document.write( "So time taken = 18/x+3<BR>\n" );
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document.write( "Upstream<BR>\n" );
document.write( "the speed of the boat is x-3 mph.<BR>\n" );
document.write( "Distance is 18km.<BR>\n" );
document.write( "Time 18 / x-3 <BR>\n" );
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document.write( "Add up the two .\r<BR>\n" );
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document.write( "18/x+3 + 18/x-3 = 9/2 hours\r<BR>\n" );
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document.write( "18(x-3)+18(x+3)= 9/2(x^2-9)\r<BR>\n" );
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document.write( "18x-54+1854 = 9x^2-81 / 2\r<BR>\n" );
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document.write( "2(36x)= 9x^2-81\r<BR>\n" );
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document.write( "72x=9x^2-81\r<BR>\n" );
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document.write( "9x^2-72x-81=0 ( divide by 9)<BR>\n" );
document.write( "x^2-8x-9=0<BR>\n" );
document.write( "x^2-9x+x-9=0<BR>\n" );
document.write( "x(x-9)+1(x-9)=0<BR>\n" );
document.write( "(x+1)(x-9)=0<BR>\n" );
document.write( "x= -1 Or x=9\r<BR>\n" );
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document.write( "Speed cannot be negative<BR>\n" );
document.write( "so boat speed in still water = 9 km/hr\r<BR>\n" );
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document.write( " </SPAN>\n" );
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