document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=220956>Question 220956</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The speed of a boat in still water is 10mph.  It travels 15 miles upstream and 15 downstream in a total of 4 hours. what is the speed of the current? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #165868 by </B><A HREF=/tutors/aboutme.mpl?userid=MathTherapy><B>MathTherapy(10552)</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=165868\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The speed of a boat in still water is 10mph.  It travels 15 miles upstream and 15 downstream in a total of 4 hours. what is the speed of the current?\r<BR>\n" );
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document.write( "Let speed of current = C\r<BR>\n" );
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document.write( "Since speed in still water is 10 mph, then the speed to go upstream, against the current = 10 - C, and the speed downstream, with the current = 10 + C\r<BR>\n" );
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document.write( "Now, since total trip took 4 hours to travel in both directions of 15 miles each, and since Time = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=D%2FS ALIGN=MIDDLE  ALT=\"D%2FS\"   DISABLED_style= \"max-width:90%; height:auto;\" >, then we'll have: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15%2F%2810+-+C%29+%2B+15%2F%2810+%2B+C%29+=+4 ALIGN=MIDDLE  ALT=\"15%2F%2810+-+C%29+%2B+15%2F%2810+%2B+C%29+=+4\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "15(10 + C) + 15(10 - C) = 4 * (10 - C)(10 + C) ----- Multiplying by LCD (10 - C)(10 + C), in order to get rid of denominators\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=150+%2B+15C+%2B+150+-+15C+=+4%28100+-+C%5E2%29 ALIGN=MIDDLE  ALT=\"150+%2B+15C+%2B+150+-+15C+=+4%28100+-+C%5E2%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=150+%2B+15C+%2B+150+-+15C+=+400+-+4C%5E2 ALIGN=MIDDLE  ALT=\"150+%2B+15C+%2B+150+-+15C+=+400+-+4C%5E2\"   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=4C%5E2+=+400+-+300 ALIGN=MIDDLE  ALT=\"4C%5E2+=+400+-+300\"   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=4C%5E2+=+100 ALIGN=MIDDLE  ALT=\"4C%5E2+=+100\"   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=C%5E2+=+100%2F4 ALIGN=MIDDLE  ALT=\"C%5E2+=+100%2F4\"   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=C%5E2+=+25 ALIGN=MIDDLE  ALT=\"C%5E2+=+25\"   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=C+=+sqrt%2825%29+=+5 ALIGN=MIDDLE  ALT=\"C+=+sqrt%2825%29+=+5\"   DISABLED_style= \"max-width:90%; height:auto;\" > mph\r<BR>\n" );
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document.write( "Therefore, speed of current = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight_green%285%29 ALIGN=MIDDLE  ALT=\"highlight_green%285%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > mph \r<BR>\n" );
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document.write( "Check<BR>\n" );
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document.write( "Time upstream: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15%2F%2810+-+5%29 ALIGN=MIDDLE  ALT=\"15%2F%2810+-+5%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15%2F5+=+3 ALIGN=MIDDLE  ALT=\"15%2F5+=+3\"   DISABLED_style= \"max-width:90%; height:auto;\" > hours\r<BR>\n" );
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document.write( "Time downstream: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15%2F%2810+%2B+5%29 ALIGN=MIDDLE  ALT=\"15%2F%2810+%2B+5%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15%2F15+=+1 ALIGN=MIDDLE  ALT=\"15%2F15+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" > hour\r<BR>\n" );
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document.write( "Total time: (3 + 1) = 4 hours\r<BR>\n" );
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