document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=119382>Question 119382</A>: <I><SPAN STYLE=\"word-break: break-all;\"> \r<BR>\n" );
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document.write( "A plane flies 720 mi against a steady 30-mi/h headwind<BR>\n" );
document.write( "and then returns to the same point with the wind. If the entire trip takes 10 h, what is the plane’s speed in still air? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #87589 by </B><A HREF=/tutors/aboutme.mpl?userid=checkley71><B>checkley71(8403)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=checkley71><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=87589\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 720/(r-30)+720/(r+30)=10<BR>\n" );
document.write( "[720(r+30)+720(r-30)]/(r^2-900)=10<BR>\n" );
document.write( "(720r+21,600+720r-21,600)/(r^2-900)=10 now cross multiply<BR>\n" );
document.write( "10(r^2-9000)=1440r<BR>\n" );
document.write( "10r^2-1440r-9000=0<BR>\n" );
document.write( "10(r^2-144r-900)=0<BR>\n" );
document.write( "10(x-150)(x+6)=0<BR>\n" );
document.write( "x-150=0<BR>\n" );
document.write( "x=150 for the speed of the airplane.<BR>\n" );
document.write( "proof<BR>\n" );
document.write( "720/(150-30)+720/(150+30)=10<BR>\n" );
document.write( "720/120+720/180=10<BR>\n" );
document.write( "6+4=10<BR>\n" );
document.write( "10=10<BR>\n" );
document.write( " </SPAN>\n" );
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