document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=592150>Question 592150</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 	Lisa drove 100 miles, then increased her speed by 25 miles per hour for 225 miles. If the second part of the drive took 1 hour longer than the first part, find her average speed. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #375909 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=375909\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> drove 100 miles, then increased her speed by 25 miles per hour for 225 miles.<BR>\n" );
document.write( " If the second part of the drive took 1 hour longer than the first part, find her average speed.<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Let s = speed the 1s 100 miles<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(s+25) = speed on the last 225 miles<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Write a time equation; time = dist/speed<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=225%2F%28%28s%2B25%29%29 ALIGN=MIDDLE  ALT=\"225%2F%28%28s%2B25%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%2Fs ALIGN=MIDDLE  ALT=\"100%2Fs\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1<BR>\n" );
document.write( "multiply by s(s+25)<BR>\n" );
document.write( "s(s+25)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=225%2F%28%28s%2B25%29%29 ALIGN=MIDDLE  ALT=\"225%2F%28%28s%2B25%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > - s(s+25)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%2Fs ALIGN=MIDDLE  ALT=\"100%2Fs\"   DISABLED_style= \"max-width:90%; height:auto;\" > = s(s+25)<BR>\n" );
document.write( "225s - 100(s+25) = s^2 + 25s<BR>\n" );
document.write( "225s - 100s - 2500 = s^2 + 25s<BR>\n" );
document.write( "125s - 2500 = s^2 + 25s<BR>\n" );
document.write( "0 = s^2 + 25s - 125s + 2500<BR>\n" );
document.write( "A quadratic equation<BR>\n" );
document.write( "s^2 - 100s + 2500 = 0<BR>\n" );
document.write( "Factors to:<BR>\n" );
document.write( "(s-50)(s-50) = 0<BR>\n" );
document.write( "s = 50 mph on the 1st 100 mi<BR>\n" );
document.write( "then<BR>\n" );
document.write( "75 mph on last 225 mi<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Let a = average speed for the whole trip which was 325 mi<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%2F50 ALIGN=MIDDLE  ALT=\"100%2F50\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=225%2F75 ALIGN=MIDDLE  ALT=\"225%2F75\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=325%2Fa ALIGN=MIDDLE  ALT=\"325%2Fa\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "multiply by 150a to clear the denominators; results<BR>\n" );
document.write( "3a(100) + 2a(225) = 150(325)<BR>\n" );
document.write( "300a + 450a = 48750<BR>\n" );
document.write( "750a = 48750<BR>\n" );
document.write( "a = 65 mph is the average speed for the trip<BR>\n" );
document.write( ":<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Check this out with a time equation<BR>\n" );
document.write( "100/50 + 225/75 = 325/65<BR>\n" );
document.write( "2 + 3 = 5 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );