document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=129394>Question 129394</A>: <I><SPAN STYLE=\"word-break: break-all;\"> My homework problem:  <BR>\n" );
document.write( "If increase the average speed of a 189 mile trip by 12mph will make the same trip one hour shorter.What is the original average speed?\r<BR>\n" );
document.write( "\n" );
document.write( "I think I have 2 equations:  \r<BR>\n" );
document.write( "\n" );
document.write( "1) vt=189mph<BR>\n" );
document.write( "2) v+12mph =  189mph/ (t-1h) \r<BR>\n" );
document.write( "\n" );
document.write( "How do I solve for V?  I tried substitution of 1) into 2) but got confused in how to solve for v in the next step. Thanks for your help. Jp </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #94532 by </B><A HREF=/tutors/aboutme.mpl?userid=Fombitz><B>Fombitz(32388)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Fombitz><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=Fombitz><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=94532\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Rate times time equals distance.<BR>\n" );
document.write( "Your two equations are correct but watch the units.<BR>\n" );
document.write( "It's 189 miles, not mph. <BR>\n" );
document.write( "1. <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=vt=189 ALIGN=MIDDLE  ALT=\"vt=189\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "2. <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28v%2B12%29%28t-1%29=189 ALIGN=MIDDLE  ALT=\"%28v%2B12%29%28t-1%29=189\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "To solve you use one of the equations to get an expression for one of the variables in terms of the other and then substitute. <BR>\n" );
document.write( "From 1,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=vt=189 ALIGN=MIDDLE  ALT=\"vt=189\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=v=189%2Ft ALIGN=MIDDLE  ALT=\"v=189%2Ft\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Now substitute this value into 2,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28v%2B12%29%28t-1%29=189 ALIGN=MIDDLE  ALT=\"%28v%2B12%29%28t-1%29=189\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28189%2Ft%2B12%29%28t-1%29=189 ALIGN=MIDDLE  ALT=\"%28189%2Ft%2B12%29%28t-1%29=189\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "Multiply both sides by t.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%28189%2Ft%2B12%29%28t-1%29=189t ALIGN=MIDDLE  ALT=\"t%28189%2Ft%2B12%29%28t-1%29=189t\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28189%2B12t%29%28t-1%29=189t ALIGN=MIDDLE  ALT=\"%28189%2B12t%29%28t-1%29=189t\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "Use the FOIL method for the left hand side,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28189%29%28t%29%2B%28189%29%28-1%29%2B%2812t%29%28t%29%2B%2812t%29%28-1%29=189t ALIGN=MIDDLE  ALT=\"%28189%29%28t%29%2B%28189%29%28-1%29%2B%2812t%29%28t%29%2B%2812t%29%28-1%29=189t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=189t-189%2B12t%5E2-12t=189t ALIGN=MIDDLE  ALT=\"189t-189%2B12t%5E2-12t=189t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=12t%5E2-12t-189=0 ALIGN=MIDDLE  ALT=\"12t%5E2-12t-189=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4t%5E2-4t-63=0 ALIGN=MIDDLE  ALT=\"4t%5E2-4t-63=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "You can factor this equation into,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%282t-9%29%282t%2B7%29=0 ALIGN=MIDDLE  ALT=\"%282t-9%29%282t%2B7%29=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "There are two solutions,<BR>\n" );
document.write( "The first solution is,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2t-9=0 ALIGN=MIDDLE  ALT=\"2t-9=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t=9%2F2 ALIGN=MIDDLE  ALT=\"t=9%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The second solution is,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2t%2B7=0 ALIGN=MIDDLE  ALT=\"2t%2B7=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t=-7%2F2 ALIGN=MIDDLE  ALT=\"t=-7%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "For your equation, t represents time.<BR>\n" );
document.write( "A negative time does not make sense in this application. <BR>\n" );
document.write( "You would use the positive answer for your solution.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t=9%2F2 ALIGN=MIDDLE  ALT=\"t=9%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Check your answer.<BR>\n" );
document.write( "1. <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=vt=189 ALIGN=MIDDLE  ALT=\"vt=189\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=v%289%2F2%29=189 ALIGN=MIDDLE  ALT=\"v%289%2F2%29=189\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=v=42 ALIGN=MIDDLE  ALT=\"v=42\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "2. <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28v%2B12%29%28t-1%29=189 ALIGN=MIDDLE  ALT=\"%28v%2B12%29%28t-1%29=189\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2842%2B12%29%289%2F2-1%29=189 ALIGN=MIDDLE  ALT=\"%2842%2B12%29%289%2F2-1%29=189\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%289%2F2-2%2F2%29=189%2F54 ALIGN=MIDDLE  ALT=\"%289%2F2-2%2F2%29=189%2F54\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7%2F2=7%2F2 ALIGN=MIDDLE  ALT=\"7%2F2=7%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Your answer leads to a true statement, it's a good answer.<BR>\n" );
document.write( "The original average speed is 42 mph.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );