document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=77740>Question 77740</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Science and medicine. 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?<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #55757 by </B><A HREF=/tutors/aboutme.mpl?userid=checkley75><B>checkley75(3666)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=checkley75><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=55757\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 720/(x-30)+720/(x+30)=10<BR>\n" );
document.write( "(720[x+30]+720[x-30])/(x-30)(x+30)=10<BR>\n" );
document.write( "10(x^2-900)=720x+21600+720x-21600<BR>\n" );
document.write( "10x^2-9000=1440x<BR>\n" );
document.write( "10x^2-1440x-9000=0<BR>\n" );
document.write( "x^2-144x-900=0<BR>\n" );
document.write( "(x-150)(x+6)=0<BR>\n" );
document.write( "x-150=0<BR>\n" );
document.write( "x=150 answer for ther plane's speed in still air.<BR>\n" );
document.write( "proof<BR>\n" );
document.write( "720/120+720/180=10<BR>\n" );
document.write( "6+4=10  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );