document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=414660>Question 414660</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A plane traveled 756 miles to Shanghai and back. the trip was with wind. it took 9 hours. the trip back was into the air. the trip back took 18 hours. find the speed of the plane in still air and the speed of the wind. \r<BR>\n" );
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document.write( "so far..i divided 756/9 = 84 (wind) and i divided 756/18 = 42(air)<BR>\n" );
document.write( "but i don't know how to set the equation up.\r<BR>\n" );
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document.write( "if you could that would be great! :)    </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #290861 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=290861\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> You have 2 trips, each one is 756 mi.<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s ALIGN=MIDDLE  ALT=\"s\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the speed of the plane in still air<BR>\n" );
document.write( "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;\" > = the wind speed<BR>\n" );
document.write( "Speed with the wind = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+%2B+w ALIGN=MIDDLE  ALT=\"s+%2B+w\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Speed against the wind = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+-+w ALIGN=MIDDLE  ALT=\"s+-+w\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d+=+756 ALIGN=MIDDLE  ALT=\"d+=+756\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi<BR>\n" );
document.write( "----------------------<BR>\n" );
document.write( "given:<BR>\n" );
document.write( "With the wind:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+%28s+%2B+w%29%2A9 ALIGN=MIDDLE  ALT=\"756+=+%28s+%2B+w%29%2A9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "against the wind:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+%28s+-+w%29%2A18 ALIGN=MIDDLE  ALT=\"756+=+%28s+-+w%29%2A18\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-----------------<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+%28s+%2B+w%29%2A9 ALIGN=MIDDLE  ALT=\"756+=+%28s+%2B+w%29%2A9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=84+=+s+%2B+w+ ALIGN=MIDDLE  ALT=\"84+=+s+%2B+w+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+%28s+-+w%29%2A18 ALIGN=MIDDLE  ALT=\"756+=+%28s+-+w%29%2A18\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=42+=+s+-+w+ ALIGN=MIDDLE  ALT=\"42+=+s+-+w+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "Add equations (1) and (2)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=126+=+2s ALIGN=MIDDLE  ALT=\"126+=+2s\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+63 ALIGN=MIDDLE  ALT=\"s+=+63\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=42+=+s+-+w+ ALIGN=MIDDLE  ALT=\"42+=+s+-+w+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=42+=+63+-+w+ ALIGN=MIDDLE  ALT=\"42+=+63+-+w+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=w+=+63+-+42 ALIGN=MIDDLE  ALT=\"w+=+63+-+42\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=w+=+21 ALIGN=MIDDLE  ALT=\"w+=+21\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The speed of the plane in still air is 63 mi/hr<BR>\n" );
document.write( "The wind speed is 21 mi/hr<BR>\n" );
document.write( "check answers:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+%28s+%2B+w%29%2A9 ALIGN=MIDDLE  ALT=\"756+=+%28s+%2B+w%29%2A9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+%2863+%2B+21%29%2A9 ALIGN=MIDDLE  ALT=\"756+=+%2863+%2B+21%29%2A9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+84%2A9 ALIGN=MIDDLE  ALT=\"756+=+84%2A9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+756 ALIGN=MIDDLE  ALT=\"756+=+756\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+%28s+-+w%29%2A18 ALIGN=MIDDLE  ALT=\"756+=+%28s+-+w%29%2A18\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+%2863+-+21%29%2A18 ALIGN=MIDDLE  ALT=\"756+=+%2863+-+21%29%2A18\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756+=+42%2A18 ALIGN=MIDDLE  ALT=\"756+=+42%2A18\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=756++=+756 ALIGN=MIDDLE  ALT=\"756++=+756\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK<BR>\n" );
document.write( "In practical terms, I don't think an airplane could<BR>\n" );
document.write( "stay in the air doing only 63 mi/hr, but I think my method is good. </SPAN>\n" );
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