document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=423740>Question 423740</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Tina is training for a biathlon. To train for the running portion of the race, she runs 10 miles each day, over the same course. The first 4 miles of the course is on level ground, while the last 6 miles is downhill. She runs 4 miles per hour slower on level ground than she runs downhill. If the complete course takes 1 hour, how fast does she run on the downhill part of the course </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #295650 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=295650\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> runs 10 miles each day, over the same course.<BR>\n" );
document.write( " The first 4 miles of the course is on level ground, while the last 6 miles is downhill.<BR>\n" );
document.write( " She runs 4 miles per hour slower on level ground than she runs downhill.<BR>\n" );
document.write( " If the complete course takes 1 hour, how fast does she run on the downhill part of the course?<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Let s = the speed downhill<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(s-4) = the speed on level ground<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Write a time equation: Time = dist/speed<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Downhill time + level time = 1 hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=6%2Fs ALIGN=MIDDLE  ALT=\"6%2Fs\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2F%28%28s-4%29%29 ALIGN=MIDDLE  ALT=\"4%2F%28%28s-4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1<BR>\n" );
document.write( "Multiply by s(s-4)*<BR>\n" );
document.write( "s(s-4)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=6%2Fs ALIGN=MIDDLE  ALT=\"6%2Fs\"   DISABLED_style= \"max-width:90%; height:auto;\" > + s(s-4)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2F%28%28s-4%29%29 ALIGN=MIDDLE  ALT=\"4%2F%28%28s-4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = s(s-4)*1<BR>\n" );
document.write( "Cancel the denominators<BR>\n" );
document.write( "6(s-4) + 4s = s^2 - 4s<BR>\n" );
document.write( "6s - 24 + 4s = s^2 - 4s<BR>\n" );
document.write( "10s - 24 = s^2 - 4s<BR>\n" );
document.write( "Combine like terms on the right<BR>\n" );
document.write( "0 = s^2 - 4s - 10s + 24<BR>\n" );
document.write( "A quadratic equation<BR>\n" );
document.write( "s^2 - 14s + 24 = 0<BR>\n" );
document.write( "Factors to<BR>\n" );
document.write( "(s-2)(s-12) = 0<BR>\n" );
document.write( "the reasonable solution<BR>\n" );
document.write( "s = 12 mph down hill<BR>\n" );
document.write( ":<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Check this (Level speed = 8)<BR>\n" );
document.write( "4/8 + 6/12 = 1<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );