document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=808958>Question 808958</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the current in a stream moves at a speed of 9 mph. a boat travels 4 mi upstream and 4 mi downstream in a total of 4 hours. what is the speed 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 #487335 by </B><A HREF=/tutors/aboutme.mpl?userid=MathTherapy><B>MathTherapy(10551)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=MathTherapy><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=MathTherapy><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=487335\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "the current in a stream moves at a speed of 9 mph. a boat travels 4 mi upstream and 4 mi downstream in a total of 4 hours. what is the speed of the boat in still water?\r<BR>\n" );
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document.write( "Let speed of boat in still water be S<BR>\n" );
document.write( "Then average speed upstream = S – 9, and average speed downstream = S + 9\r<BR>\n" );
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document.write( "Therefore, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2F%28S+-+9%29+%2B+4%2F%28S+%2B+9%29+=+4 ALIGN=MIDDLE  ALT=\"4%2F%28S+-+9%29+%2B+4%2F%28S+%2B+9%29+=+4\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "4(S + 9) + 4(S – 9) = 4(S - 9)(S + 9) ------ Multiplying by LCD, (S – 9)(S  + 9)\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4S+%2B+36+%2B+4S+-+36+=+4%28S%5E2+-+81%29 ALIGN=MIDDLE  ALT=\"4S+%2B+36+%2B+4S+-+36+=+4%28S%5E2+-+81%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=8S+=+4%28S%5E2+-+81%29 ALIGN=MIDDLE  ALT=\"8S+=+4%28S%5E2+-+81%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=4%282S%29+=+4%28S%5E2+-+81%29 ALIGN=MIDDLE  ALT=\"4%282S%29+=+4%28S%5E2+-+81%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=2S+=+S%5E2+-+81 ALIGN=MIDDLE  ALT=\"2S+=+S%5E2+-+81\"   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=S%5E2+-+2S+-+81+=+0 ALIGN=MIDDLE  ALT=\"S%5E2+-+2S+-+81+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Using the quadratic formula, the speed of the boat in still water = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight_green%2810.05538514%29 ALIGN=MIDDLE  ALT=\"highlight_green%2810.05538514%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > mph\r<BR>\n" );
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document.write( "You can do the check!! \r<BR>\n" );
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document.write( "Send comments, “thank-yous,” and inquiries to “D” at MathMadEzy@aol.com. Further help is available, online or in-person, for a fee, obviously. \r<BR>\n" );
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