document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=418530>Question 418530</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a fast plane making a 2400 mile trip was delayed 14 minutes before take off because of bad weather. To make up for the delay, the pilot increased his airspeed and took a favorable tailwind. Thus he was able to average 6 miles per hour more than usual. Find the usual average ground speed and flying time for the trip.\r<BR>\n" );
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document.write( "I know the first equation is (x+6)*(y+(14/60))=2400 but i can't figure out the second equation to do a system of equations.<BR>\n" );
document.write( "(x=average airspeed   y=flying time) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #292896 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=292896\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> average speed =x<BR>\n" );
document.write( "time = y\r<BR>\n" );
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document.write( "..<BR>\n" );
document.write( "xy=2400<BR>\n" );
document.write( "x=2400/y<BR>\n" );
document.write( "(x+6)(y-14/60)= 2400<BR>\n" );
document.write( "(x+6)(60y-14)/60=2400<BR>\n" );
document.write( "(x+6)(60y-14)=60*2400<BR>\n" );
document.write( "plug x<BR>\n" );
document.write( "(2400/y +6)(60y-14)=60*2400<BR>\n" );
document.write( "(2400+6y)(60y-14)/y=144000<BR>\n" );
document.write( "(2400+6y)(60y-14)=144000y<BR>\n" );
document.write( "6(400+y)*2(30y-7)=144000y<BR>\n" );
document.write( "(400+y)(30y-7)=144000y/12<BR>\n" );
document.write( "12000y-2800+30y^2-7y=12000y<BR>\n" );
document.write( "30y^2-7y-2800=0\r<BR>\n" );
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document.write( "solve using quadratic formula<BR>\n" );
document.write( "b^2-4ac=336049<BR>\n" );
document.write( "...<BR>\n" );
document.write( "y=9.78 hours<BR>\n" );
document.write( "x=2400/9.78 = 245.4 mph </SPAN>\n" );
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