document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=953679>Question 953679</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An airplane flies 1000 miles in two hours. The return flight against the wind took 2.5 hours. Find the airplane's speed in still air and the speed of the wind. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #582481 by </B><A HREF=/tutors/aboutme.mpl?userid=addingup><B>addingup(3677)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=addingup><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=addingup><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=582481\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Since it takes 2 hours to cover 1000 miles, that is 1000/2 = 500 mile per hour. And coming back against the same wind, the speed is 1000/2.5 = 400 miles per hour.\r<BR>\n" );
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document.write( "Let a be the air speed and w the wind speed:\r<BR>\n" );
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document.write( "a + w = 500<BR>\n" );
document.write( "a – w = 400 Let’s add the two equations:<BR>\n" );
document.write( "a + w + a – w = 500 + 400 Complete the additions on both sides:<BR>\n" );
document.write( "2a = 900<BR>\n" );
document.write( "a = 900/2<BR>\n" );
document.write( "a = 450 is the plane’s speed in still air. Now substitute in the first equation:<BR>\n" );
document.write( "450 + w = 500 Subtract 450 on both sides<BR>\n" );
document.write( "w = 50 is the wind speed<BR>\n" );
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