document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1058175>Question 1058175</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A truck traveled the first 100 miles of a trip at one speed and the last 135 miles at an average speed of 5 miles per hour less. The entire trip took 5 hours. What was the average speed for the first part of the trip? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #673220 by </B><A HREF=/tutors/aboutme.mpl?userid=ewatrrr><B>ewatrrr(24785)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ewatrrr><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=ewatrrr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=673220\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> D = rt  0r t = D/r<BR>\n" );
document.write( "100/r + 135/(r-5) = 5hr<BR>\n" );
document.write( "100(r-5) + 135r = 5r(r-5)<BR>\n" );
document.write( "5r^2 - 25r - 100r +500 - 135r = 0<BR>\n" );
document.write( "5r^2 - 260r + 500 = 0<BR>\n" );
document.write( "r^3 - 52r + 100 = 0<BR>\n" );
document.write( "(r-50)(r-2) = 0<BR>\n" );
document.write( "r = 50mph, the average speed for the first part of the trip<BR>\n" );
document.write( "checking:<BR>\n" );
document.write( "100mi/50mph + 135mi/45mph = 2hr + 3hr = 5hr  CHECKS! </SPAN>\n" );
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