document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=219289>Question 219289</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A homing device left its home to deliver a mesage. on takeoff, the device encountered a tailwind of 15 mph and made the delivery in 5 minutes. The return trip into the wind took 10 minutes. How fast does the device fly in still air?\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "llaws@mrhs.com<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 #164940 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=164940\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A homing device left its home to deliver a mesage. on takeoff, the device encountered a tailwind of 15 mph and made the delivery in 5 minutes. The return trip into the wind took 10 minutes. How fast does the device fly in still air? <BR>\n" );
document.write( "----------<BR>\n" );
document.write( "Let x be the rate of the device in still air.<BR>\n" );
document.write( "------------------<BR>\n" );
document.write( "Downwind DATA:<BR>\n" );
document.write( "time = 1/12 hr ; rate = x+15 mph ; distance = rt = (1/12)(x+15) miles<BR>\n" );
document.write( "-------------------------<BR>\n" );
document.write( "Upwind DATA:<BR>\n" );
document.write( "time = 1/6 hr ; rate = x-15 mph ; distance = rt = (1/6)(x-15) miles<BR>\n" );
document.write( "-------------------------<BR>\n" );
document.write( "Equation:<BR>\n" );
document.write( "distance = distance<BR>\n" );
document.write( "(1/12)(x+15) = (1/6)(x-15)<BR>\n" );
document.write( "Multiply both sides by 12 to get:<BR>\n" );
document.write( "x+15 = 2x-30<BR>\n" );
document.write( "x = 45 mph (speed of the device in still air)<BR>\n" );
document.write( "==================================================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );