document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=122329>Question 122329</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Junior drove his rig on Interstate 10 prom San Antonio to El Paso.  At the halfway point he noticed that he had been averaging 80 MPH, while his company requires his average speed to be 60 mph.  What must his spped for the last half of the trip be so that he will average 60 mph for the entire trip?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #89816 by </B><A HREF=/tutors/aboutme.mpl?userid=checkley71><B>checkley71(8403)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=checkley71><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=89816\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .5/80+.5/x=1/60<BR>\n" );
document.write( "(.5x+.5*80)/80x=1/60 now cross multiply.<BR>\n" );
document.write( "80x=60(.5x+40)<BR>\n" );
document.write( "80x=30x+2400<BR>\n" );
document.write( "80x-30x=2400<BR>\n" );
document.write( "50x=2400<BR>\n" );
document.write( "x=2400/50<BR>\n" );
document.write( "x=48 mph must be the speed for the last half of the trip.<BR>\n" );
document.write( "proof<BR>\n" );
document.write( ".5/80+.5/48=1/60<BR>\n" );
document.write( "(.5*48+.5*80)/80*48=1/60<BR>\n" );
document.write( "(24+40)/3840=1/60<BR>\n" );
document.write( "64/3840=1/60<BR>\n" );
document.write( "1/60=1/60 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );