document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=99494>Question 99494</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 20 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 #72489 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=72489\">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 20 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 the boat in still water<BR>\n" );
document.write( "Then<BR>\n" );
document.write( "(s+4) = speed down-stream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(s-4) = speed up-stream<BR>\n" );
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document.write( "Since we are dealing in mph, change 20 min to hrs: 20/60 = 1/3 hr<BR>\n" );
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document.write( "Write a time equation: Time = distance/speed<BR>\n" );
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document.write( "Time up-stream - Time down-stream = 1/3 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=1%2F3 ALIGN=MIDDLE  ALT=\"1%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "Multiply equation by 3(s-4)(s+4), eliminates the denominator, resulting in:<BR>\n" );
document.write( "3(s+4)*5 - 3(s-4)*5  = (s+4)(s-4)<BR>\n" );
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document.write( "15(s+4) - 15(s-4) = s^2 - 16<BR>\n" );
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document.write( "15s + 60 - 15s + 60 = s^2 - 16<BR>\n" );
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document.write( "120 = s^2 -16<BR>\n" );
document.write( "or<BR>\n" );
document.write( "s^2 - 16 = 120<BR>\n" );
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document.write( "s^2 = 120 + 16<BR>\n" );
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document.write( "s^2 = 136<BR>\n" );
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document.write( "s = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%28136%29 ALIGN=MIDDLE  ALT=\"sqrt%28136%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "s = 11.66 mph in still water<BR>\n" );
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document.write( "Check solution by finding the times:<BR>\n" );
document.write( "5/(11.66-4) = .6527 hrs<BR>\n" );
document.write( "5/(11.66+4) = .3193<BR>\n" );
document.write( "-------------------<BR>\n" );
document.write( "difference  = .3334 hrs which ~ 20 min<BR>\n" );
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document.write( "How about this? Did it make sense to you?<BR>\n" );
document.write( " </SPAN>\n" );
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