document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=80880>Question 80880</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 #58040 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=58040\">put this solution on YOUR website!</A><BR><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? <BR>\n" );
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document.write( "let x = boat speed in still water<BR>\n" );
document.write( "Then:<BR>\n" );
document.write( "(x-4) = speed up-stream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(x+4) = speed down 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 = dist/speed<BR>\n" );
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document.write( "Time down-stream + 1/3 hr = time upstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F%28%28x%2B4%29%29 ALIGN=MIDDLE  ALT=\"5%2F%28%28x%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;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F%28%28x-4%29%29 ALIGN=MIDDLE  ALT=\"5%2F%28%28x-4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "Multiply equation by 3(x+4)(x-4) to get rid of the denominators, you then have;<BR>\n" );
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document.write( "15(x-4) + (x+4)(x-4) = 15(x+4)<BR>\n" );
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document.write( "15x - 60 + x^2 - 16 = 15x + 60; multiplied what's inside the brackets<BR>\n" );
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document.write( "x^2 + 15x - 15x  = + 60 + 60 + 16; x's on the left, numbers on the right<BR>\n" );
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document.write( "x^2 = 136<BR>\n" );
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document.write( "x = <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( "x = 11.66 mph in still water<BR>\n" );
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document.write( "Check solution by finding the times<BR>\n" );
document.write( "Speed up = 7.66, speed down = 15.66<BR>\n" );
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document.write( "5/7.66  = .65 hr<BR>\n" );
document.write( "5/15.66 = .32<BR>\n" );
document.write( "---------------<BR>\n" );
document.write( "subtract= .33 hr difference, check our solution of x = 11.66 </SPAN>\n" );
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