document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=77448>Question 77448</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A six passenger plane cruises at 180 mph in calm air. If the plane flies 7 miles with the wind in the same amount of time as it flies 5 miles against the wind, then what is the wind speed? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #55567 by </B><A HREF=/tutors/aboutme.mpl?userid=ptaylor><B>ptaylor(2198)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ptaylor><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=ptaylor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=55567\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Distance (d)= rate(r) times time (t) or d=rt; t=d/r \r<BR>\n" );
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document.write( "Let x=rate of speed of wind\r<BR>\n" );
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document.write( "Speed of plane with wind =180+x<BR>\n" );
document.write( "Distance travelled with wind is 7 mi<BR>\n" );
document.write( "Time to travel 7 mi with wind is 7/(180+x)-----Time #1<BR>\n" );
document.write( "Speed of plane against wind=180-x<BR>\n" );
document.write( "Distance travelled against wind is 5 mi<BR>\n" );
document.write( "Time to travel 5 mi against wind is 5/(180-x)----Time #2\r<BR>\n" );
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document.write( "Now we are told that Time #1 = Time #2  so our equation to solve is:\r<BR>\n" );
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document.write( "7/(180+x)=5/(180-x)  Multiply both sides by (180+x)(180-x) to get rid of the fractions:\r<BR>\n" );
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document.write( "7(180+x)(180-x)/(180+x)=5(180+x)(180-x)/(180-x) Simplify by cancelling\r<BR>\n" );
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document.write( "7(180-x)=5(180+x)  get rid of parens<BR>\n" );
document.write( "1260-7x=900+5x  subtract 1260 and also 5x from both sides\r<BR>\n" );
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document.write( "1260-1260-7x-5x=900-1260+5x-5x  collect like terms\r<BR>\n" );
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document.write( "-12x=-360  divide both sides by -12\r<BR>\n" );
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document.write( "x=30 mph--------------------speed of the wind\r<BR>\n" );
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document.write( "CK <BR>\n" );
document.write( " t=d/r<BR>\n" );
document.write( "7/(180+30)=5/(180-30)<BR>\n" );
document.write( "7/210=5/150<BR>\n" );
document.write( "1/30=1/30\r<BR>\n" );
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document.write( "Hope this helps----ptaylor\r<BR>\n" );
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document.write( " </SPAN>\n" );
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