document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=511994>Question 511994</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a twin engine aircraft can fly 720 miles from a city \"a\" to a city \"b\" in 4 hours with the wind and make a return in 6 hours against the wind. what is 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 #342473 by </B><A HREF=/tutors/aboutme.mpl?userid=oberobic><B>oberobic(2304)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=oberobic><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=342473\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> d = r*t is the fundamental distance equation.<BR>\n" );
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document.write( "Fly to B:<BR>\n" );
document.write( "r = airspeed + wind speed = (a + w) mph<BR>\n" );
document.write( "t = 4 hr<BR>\n" );
document.write( "d = 720 mi<BR>\n" );
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document.write( "Return to A:<BR>\n" );
document.write( "r= airspeed -wind speed = (a - w) mph<BR>\n" );
document.write( "t = 6 hr<BR>\n" );
document.write( "d = 720 mi<BR>\n" );
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document.write( "6a - 6w = 720<BR>\n" );
document.write( "4a + 4w = 720<BR>\n" );
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document.write( "12a - 12w = 1440<BR>\n" );
document.write( "12a + 12w = 2160<BR>\n" );
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document.write( "0a -24w = -720<BR>\n" );
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document.write( "w = 30 = wind speed<BR>\n" );
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document.write( "substitute w=30 to find airspeed<BR>\n" );
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document.write( "6a - 6(30) = 720<BR>\n" );
document.write( "6a = 720 + 180<BR>\n" );
document.write( "6a = 900<BR>\n" );
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document.write( "a = 150 = airspeed<BR>\n" );
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document.write( "Check to see if it can cover the distances in the correct times.<BR>\n" );
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document.write( "(150-30)*6 = ??<BR>\n" );
document.write( "120*6 = 720<BR>\n" );
document.write( "correct<BR>\n" );
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document.write( "(150+30)*4 = ??<BR>\n" );
document.write( "(180)*4 = 720<BR>\n" );
document.write( "correct<BR>\n" );
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document.write( "Answer:  The wind speed is 30 mph.<BR>\n" );
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document.write( "Done. </SPAN>\n" );
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