document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=69986>Question 69986</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am having a difficult time with this problem. Rita rows 12 km upstream and 12 km downstream in 3 hours. The speed of her boat in still water is 9 km/hr. Find the speed of the stream. Someone please help? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #49846 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=49846\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I am having a difficulty time with this problem. Rita rows 12 km upstream and 12 km downstream in 3 hours. The speed of her boat in still water is 9 km/hr. Find the speed of the stream.<BR>\n" );
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document.write( "let x = speed of the stream:<BR>\n" );
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document.write( "Speed upstream = (9-x)<BR>\n" );
document.write( "Speed downstream = (9+x)<BR>\n" );
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document.write( "Time = dist/speed<BR>\n" );
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document.write( "Time upstream + time downstream = 3 hrs<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=12%2F%28%289-x%29%29+%2B+12%2F%28%289%2Bx%29%29 ALIGN=MIDDLE  ALT=\"12%2F%28%289-x%29%29+%2B+12%2F%28%289%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 3<BR>\n" );
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document.write( "Multiply equation by (9-x)(9+x), results<BR>\n" );
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document.write( "12(9+x) + 12(9-x) = 3(9-x)(9+x)<BR>\n" );
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document.write( "108 + 12x + 108 - 12x = 3(81 - x^2); difference of squares<BR>\n" );
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document.write( "216 = 243 - 3x^2; 12x's eliminated<BR>\n" );
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document.write( "0 = 243 - 216 - 3x^2<BR>\n" );
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document.write( "+3x^2 = 243 - 216<BR>\n" );
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document.write( "3x^2 = 27<BR>\n" );
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document.write( "x^2 = 27/3<BR>\n" );
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document.write( "x^2 = 9<BR>\n" );
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document.write( "x = SqRt(9)<BR>\n" );
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document.write( "x = 3 mph speed of the stream<BR>\n" );
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document.write( "Check our solution: speed up is 6, speed down is 12<BR>\n" );
document.write( "12/12 + 12/6 = 3 hrs<BR>\n" );
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document.write( "Did this make sense to you?\r<BR>\n" );
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