document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=793207>Question 793207</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Al was able to ride his bike 36mph with the wind, and 24 mph against the wind.  The wind speed was 3mph.  How fast does he ride with no wind?\r<BR>\n" );
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document.write( "Just looking at problem the answer should be 30.  But when I try to use a formula I don't get 30.\r<BR>\n" );
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document.write( "t=d/r<BR>\n" );
document.write( "36/x+3=24/x-3<BR>\n" );
document.write( "36(x-3)=24(x+3)<BR>\n" );
document.write( "36x-108=24x+72<BR>\n" );
document.write( "12x=180<BR>\n" );
document.write( "x=15<BR>\n" );
document.write( "what am I doing wrong? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #480282 by </B><A HREF=/tutors/aboutme.mpl?userid=KMST><B>KMST(5328)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=KMST><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=KMST><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=480282\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The problem does not make sense to me,<BR>\n" );
document.write( "but what you are doing would be the solution to a different problem.<BR>\n" );
document.write( "You were given his speeds with and against the wind.<BR>\n" );
document.write( "You are also given the speed of the wind.<BR>\n" );
document.write( "The speed of the wind should not really directly add to or subtract from the speed of a bike rider.<BR>\n" );
document.write( "That works for a plane, which rides on the moving air, so the velocities are additive.<BR>\n" );
document.write( "A bike rider pushes against the ground and is slowed by a headwind but by less than the speed of the headwind. A 10mph headwind slows a cyclist by 2-5 mph (depending on many factors). A tailwind may not increase the speed by the same amount.<BR>\n" );
document.write( "If we assume the riding against the wind slows Al by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=w ALIGN=MIDDLE  ALT=\"w\"   DISABLED_style= \"max-width:90%; height:auto;\" > mph, and riding with the wind speeds him by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=w ALIGN=MIDDLE  ALT=\"w\"   DISABLED_style= \"max-width:90%; height:auto;\" > mph, compared to his speed of <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > mph with no wind, then we have the system.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=system%28x%2Bw=36%2Cx-w=24%29 ALIGN=MIDDLE  ALT=\"system%28x%2Bw=36%2Cx-w=24%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=system%28x=30%2Cw=6%29 ALIGN=MIDDLE  ALT=\"system%28x=30%2Cw=6%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "It does not make sense that a 3 mph wind could do that, but the whole problem does not make sense.<BR>\n" );
document.write( " <BR>\n" );
document.write( "Your equation and solution would be the right answer for a different problem.<BR>\n" );
document.write( "If the problem stated that in the same time that he traveled a distance of 24 miles against the wind, he traveled 36 miles with the wind, and the wind velocity was additive,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=24%2F%28x-3%29 ALIGN=MIDDLE  ALT=\"24%2F%28x-3%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > would be the time to travel 24 miles with a speed of <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x-3 ALIGN=MIDDLE  ALT=\"x-3\"   DISABLED_style= \"max-width:90%; height:auto;\" > miles per hour, against the wind,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36%2F%28x%2B3%29%7D%7D+would+be+the+time+to+travel+36+miles+with+a+speed+of+%7B%7B%7Bx%2B3 ALIGN=MIDDLE  ALT=\"36%2F%28x%2B3%29%7D%7D+would+be+the+time+to+travel+36+miles+with+a+speed+of+%7B%7B%7Bx%2B3\"   DISABLED_style= \"max-width:90%; height:auto;\" > miles per hour, with the wind,<BR>\n" );
document.write( "and the equation <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=36%2F%28x%2B3%29=24%2F%28x-3%29 ALIGN=MIDDLE  ALT=\"36%2F%28x%2B3%29=24%2F%28x-3%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > would make sense because the problem would have said that the times were the same.<BR>\n" );
document.write( "AL would be riding 2 hours against the wind with a speed of 12 mph to travel 24 miles, and he would be riding with a speed of 18 mph with the wind for 2 hours covering 36 miles. </SPAN>\n" );
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