document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=292740>Question 292740</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An airplne flew for 4 hours with a 20 km/hour tail wind.  The return flight against the same wind took 5 hours.  Find the speed of the plane in still air.\r<BR>\n" );
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document.write( "I am having trouble finding the distance flown to figure out the answer. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #211390 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=211390\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=w ALIGN=MIDDLE  ALT=\"w\"   DISABLED_style= \"max-width:90%; height:auto;\" > = wind speed<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=p ALIGN=MIDDLE  ALT=\"p\"   DISABLED_style= \"max-width:90%; height:auto;\" > = speed of plane in still air<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=p+%2B+w ALIGN=MIDDLE  ALT=\"p+%2B+w\"   DISABLED_style= \"max-width:90%; height:auto;\" > = speed of plane flying with the wind<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=p+-+w ALIGN=MIDDLE  ALT=\"p+-+w\"   DISABLED_style= \"max-width:90%; height:auto;\" > = speed of plane flying against the wind<BR>\n" );
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document.write( "Flying with the wind:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+%28p+%2B+w%29%2A4 ALIGN=MIDDLE  ALT=\"d+=+%28p+%2B+w%29%2A4\"   DISABLED_style= \"max-width:90%; height:auto;\" > km<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+%28p+%2B+20%29%2A4 ALIGN=MIDDLE  ALT=\"d+=+%28p+%2B+20%29%2A4\"   DISABLED_style= \"max-width:90%; height:auto;\" > km<BR>\n" );
document.write( "Flying against the wind:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+%28p+-+w%29%2A5 ALIGN=MIDDLE  ALT=\"d+=+%28p+-+w%29%2A5\"   DISABLED_style= \"max-width:90%; height:auto;\" > km<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+%28p+-+20%29%2A5 ALIGN=MIDDLE  ALT=\"d+=+%28p+-+20%29%2A5\"   DISABLED_style= \"max-width:90%; height:auto;\" > km<BR>\n" );
document.write( "Since <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d ALIGN=MIDDLE  ALT=\"d\"   DISABLED_style= \"max-width:90%; height:auto;\" > is the same in (1) and (2), they <BR>\n" );
document.write( "are equal to eachother<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28p+%2B+20%29%2A4+=+%28p+-+20%29%2A5 ALIGN=MIDDLE  ALT=\"%28p+%2B+20%29%2A4+=+%28p+-+20%29%2A5\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4p+%2B+80+=+5p+-+100 ALIGN=MIDDLE  ALT=\"4p+%2B+80+=+5p+-+100\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=p+=+180 ALIGN=MIDDLE  ALT=\"p+=+180\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The plane's speed in still air is 180 km/hr<BR>\n" );
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