document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1025505>Question 1025505</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A plane flies 500 miles with the wind and 350 miles against the wind in the same length of time. If the speed of the wind is 30 mph, what is the speed of the plane 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 #640807 by </B><A HREF=/tutors/aboutme.mpl?userid=fractalier><B>fractalier(6550)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=fractalier><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=fractalier><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=640807\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Time is distance over rate, t = d/r.  We will use r for the rate in still air.<BR>\n" );
document.write( "The plane's first time is t = 500/(r+30).<BR>\n" );
document.write( "The plane's second time is t = 350/(r-30).<BR>\n" );
document.write( "These are equal times, so<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=500%2F%28r%2B30%29+=+350%2F%28r-30%29 ALIGN=MIDDLE  ALT=\"500%2F%28r%2B30%29+=+350%2F%28r-30%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Now solve...<BR>\n" );
document.write( "500(r-30) = 350(r+30)<BR>\n" );
document.write( "500r - 15000 = 350r + 10500<BR>\n" );
document.write( "150r = 25500<BR>\n" );
document.write( "r = 170 mph </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );