document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=138837>Question 138837</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the 4-mph current, it took her 40 minutes longer to get there than to return. How fast will her boat go 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 #101308 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=101308\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Debbie traveled by boat 5 miles upstream. Because of the 4-mph current, it took her 40 minutes longer to get there than to return. How fast will her boat go in still water?<BR>\n" );
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document.write( "Let s = speed of boat in still water<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(s-4) = speed upstream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(s+4) = speed downstream<BR>\n" );
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document.write( "Change 40 min to hrs: 40/60 = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F3 ALIGN=MIDDLE  ALT=\"2%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" >hr<BR>\n" );
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document.write( "Write a time equation: Time = Dist/speed:<BR>\n" );
document.write( "Time upstream = time downstream + 2/3 hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F%28%28s-4%29%29 ALIGN=MIDDLE  ALT=\"5%2F%28%28s-4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F%28%28s%2B4%29%29 ALIGN=MIDDLE  ALT=\"5%2F%28%28s%2B4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F3 ALIGN=MIDDLE  ALT=\"2%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "Multiply equation by 3(s+4(s-4) to get rid of the denominators:<BR>\n" );
document.write( "3(s+4)(s-4)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F%28%28s-4%29%29 ALIGN=MIDDLE  ALT=\"5%2F%28%28s-4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 3(s+4)(s-4)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F%28%28s%2B4%29%29 ALIGN=MIDDLE  ALT=\"5%2F%28%28s%2B4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + 3(s+4)(s-4)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F3 ALIGN=MIDDLE  ALT=\"2%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Cancel out the denominators:<BR>\n" );
document.write( "3(s+4)*5 = 3(s-4)*5 + 2(s+4)(s-4)<BR>\n" );
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document.write( "15(s+4) = 15(s-4) + 2(s^2 - 16)<BR>\n" );
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document.write( "15s + 60 = 15s - 60 + 2s^2 - 32<BR>\n" );
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document.write( "0 = 2s^2 + 15s - 15s - 60 - 60 - 32; combine on the right<BR>\n" );
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document.write( "2s^2 - 152 = 0<BR>\n" );
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document.write( "2s^2 = 152<BR>\n" );
document.write( "s^2 =<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=152%2F2 ALIGN=MIDDLE  ALT=\"152%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "s = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%2876%29 ALIGN=MIDDLE  ALT=\"sqrt%2876%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "s = 8.7 mph speed in still water<BR>\n" );
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document.write( "Check the times of each trip, using decimals:<BR>\n" );
document.write( "5/4.7 = 1.064 hrs<BR>\n" );
document.write( "5/12.7 = .394 hrs<BR>\n" );
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document.write( "Differs .67 hrs; confirms our solution </SPAN>\n" );
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