document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=29434>Question 29434</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Science and medicine.  A plane flies 720 m aginst a steady 30-mi/h headwind and then returns to the same point with the wind.  If the entire trip takes <BR>\n" );
document.write( "10 h, what is the plane's speed in still air?\r<BR>\n" );
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document.write( "Thank you for your help. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #16224 by </B><A HREF=/tutors/aboutme.mpl?userid=Paul><B>Paul(988)</B></A><img src=\"/images/stars/stars-11.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Paul><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=16224\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> With the wind = x+30<BR>\n" );
document.write( "Against the wind = x-30\r<BR>\n" );
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document.write( "<font color = brown>Equation:</font><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=720%2F%28x-30%29%2B720%2F%28x%2B30%29=10 ALIGN=MIDDLE  ALT=\"720%2F%28x-30%29%2B720%2F%28x%2B30%29=10\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=720%28%28x-30%29%2B%28x%2B30%29%29=10%28%28x-30%29%28x%2B30%29%29 ALIGN=MIDDLE  ALT=\"720%28%28x-30%29%2B%28x%2B30%29%29=10%28%28x-30%29%28x%2B30%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=720%282x%29=10%28x%5E2-900%29 ALIGN=MIDDLE  ALT=\"720%282x%29=10%28x%5E2-900%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1440x=10x%5E2-9000 ALIGN=MIDDLE  ALT=\"1440x=10x%5E2-9000\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=10x%5E2-1440x-9000 ALIGN=MIDDLE  ALT=\"10x%5E2-1440x-9000\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5E2-144x-900=0 ALIGN=MIDDLE  ALT=\"x%5E2-144x-900=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=%28-%28-144%29%2B-sqrt%28%28-144%29%5E2-4%2A1%2A-900%29%29%2F%282%2A1%29 ALIGN=MIDDLE  ALT=\"x=%28-%28-144%29%2B-sqrt%28%28-144%29%5E2-4%2A1%2A-900%29%29%2F%282%2A1%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "simplfy, you get two solutions:\r<BR>\n" );
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document.write( "x=-6 and x=150\r<BR>\n" );
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document.write( "Remove the negative.<BR>\n" );
document.write( "Hence, the speed of the plane is 150mph.<BR>\n" );
document.write( "Paul. </SPAN>\n" );
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