document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=640662>Question 640662</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A roller coaster goes down the first grade 8 times faster than it goes up the other side. The distance down is 100 ft. more than the distance up, and it takes 70 seconds to go up and 10 seconds to come down. What is the speed in ft. per second of the roller coaster when it goes up and when it comes down?\r<BR>\n" );
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document.write( "I've tried a proportion:<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28d%2B100%29%2Fd+=+10%2F70+ ALIGN=MIDDLE  ALT=\"+%28d%2B100%29%2Fd+=+10%2F70+\"   DISABLED_style= \"max-width:90%; height:auto;\" > and got <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-116.666 ALIGN=MIDDLE  ALT=\"-116.666\"   DISABLED_style= \"max-width:90%; height:auto;\" > and my teacher said the answer is not a decimal but the equation is an equality. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #403354 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=403354\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A roller coaster goes down the first grade 8 times faster than it goes up the other side.<BR>\n" );
document.write( " The distance down is 100 ft. more than the distance up, and it takes 70<BR>\n" );
document.write( " seconds to go up and 10 seconds to come down.<BR>\n" );
document.write( " What is the speed in ft. per second of the roller coaster when it goes up<BR>\n" );
document.write( " and when it comes down?<BR>\n" );
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document.write( "Let s = speed going up<BR>\n" );
document.write( "then<BR>\n" );
document.write( "8s = speed coming down<BR>\n" );
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document.write( "coming down equation (speed = dist/time)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28d%2B100%29%2F10 ALIGN=MIDDLE  ALT=\"%28d%2B100%29%2F10\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 8s<BR>\n" );
document.write( "solve for d<BR>\n" );
document.write( "d + 100 = 80s<BR>\n" );
document.write( "d = 80s - 100<BR>\n" );
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document.write( "and going up equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%2F70 ALIGN=MIDDLE  ALT=\"d%2F70\"   DISABLED_style= \"max-width:90%; height:auto;\" > = s<BR>\n" );
document.write( "d = 70s<BR>\n" );
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document.write( "d=d, therefore<BR>\n" );
document.write( "80s - 100 = 70s<BR>\n" );
document.write( "80s - 70s = 100<BR>\n" );
document.write( "10s = 100<BR>\n" );
document.write( "s = 10 ft/sec going up<BR>\n" );
document.write( "then<BR>\n" );
document.write( "8(10) = 80 ft/sec going down<BR>\n" );
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document.write( "Check this by finding the actual distances<BR>\n" );
document.write( "Down: 10*80 = 800 ft<BR>\n" );
document.write( "Up: 70 * 10 = 700 ft; a dif of 100'<BR>\n" );
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