document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=539007>Question 539007</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Rashard drives 100 mi from Detroit to Lansing, and later drives 90 mi more from Lansing to Grand Rapids. The trip from Lansing to Grand Rapids takes him a half hour less than the drive from Detroit to Lansing. What is his driving average speed if it is the same on both parts 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 #353451 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=353451\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Rashard drives 100 mi from Detroit to Lansing, and later drives 90 mi more from Lansing to Grand Rapids.<BR>\n" );
document.write( " The trip from Lansing to Grand Rapids takes him a half hour less than the drive from Detroit to Lansing.<BR>\n" );
document.write( " What is his driving average speed if it is the same on both parts of the trip?<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Let t = time from Det to Lan<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(t-.5) = time from Lan to G.R.<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Write a speed equation, speed = dist/time<BR>\n" );
document.write( "Speed was the same on both trips<BR>\n" );
document.write( ":<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%2Ft ALIGN=MIDDLE  ALT=\"100%2Ft\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=90%2F%28%28t-.5%29%29 ALIGN=MIDDLE  ALT=\"90%2F%28%28t-.5%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "cross multiply<BR>\n" );
document.write( "100(t-.5) = 90t<BR>\n" );
document.write( "100t - 50 = 90t<BR>\n" );
document.write( "100t - 90t = 50<BR>\n" );
document.write( "10t = 50<BR>\n" );
document.write( "t = 50/10<BR>\n" );
document.write( "t = 5 hrs to Lansing<BR>\n" );
document.write( "Find the speed<BR>\n" );
document.write( "100/5 = 20 mph was his average speed<BR>\n" );
document.write( "check the speed<BR>\n" );
document.write( "90/4.5 = 20 mph </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );