document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=941811>Question 941811</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Juan is driving on the highway. He begins the trip with <BR>\n" );
document.write( "18<BR>\n" );
document.write( " gallons of gas in his car. The car uses up one gallon of gas every <BR>\n" );
document.write( "20<BR>\n" );
document.write( " miles.<BR>\n" );
document.write( "Let <BR>\n" );
document.write( "G<BR>\n" );
document.write( " represent the number of gallons of gas he has left in his tank, and let <BR>\n" );
document.write( "D<BR>\n" );
document.write( " represent the total distance (in miles) he has traveled. Write an equation relating <BR>\n" );
document.write( "G<BR>\n" );
document.write( " to <BR>\n" );
document.write( "D<BR>\n" );
document.write( " , and then graph your equation using the axes below. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #574131 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=574131\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> [( 1 gallon ) / ( 20 mi )] x D = ( gallons used )<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28+1%2F20+%29%2AD+ ALIGN=MIDDLE  ALT=\"+%28+1%2F20+%29%2AD+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = gallons used<BR>\n" );
document.write( "for instance, if he travels <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+D+=+40+ ALIGN=MIDDLE  ALT=\"+D+=+40+\"   DISABLED_style= \"max-width:90%; height:auto;\" >  mi, then<BR>\n" );
document.write( "( gallons used ) = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2+ ALIGN=MIDDLE  ALT=\"+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "---------------------------<BR>\n" );
document.write( "( gallons left in tank ) = ( 18 gallons ) - ( gallons used )<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+G+=+18+-+%28+1%2F20+%29%2AD+ ALIGN=MIDDLE  ALT=\"+G+=+18+-+%28+1%2F20+%29%2AD+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "This is the equation to use, but if you have to graph it,<BR>\n" );
document.write( "you need to decide which variable is dependent and<BR>\n" );
document.write( "which variable is independent.<BR>\n" );
document.write( "You have to choose between:<BR>\n" );
document.write( "(1) G depends on D<BR>\n" );
document.write( "OR<BR>\n" );
document.write( "(2) D depends on G<BR>\n" );
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document.write( "(1) is correct, because the gallons I have left in my tank<BR>\n" );
document.write( "DEPENDS on how far I have driven<BR>\n" );
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document.write( "So, G is the DEPENDENT variable, and that makes<BR>\n" );
document.write( "D the INDEPENDENT variable<BR>\n" );
document.write( "----------------------<BR>\n" );
document.write( "The independent variable is always plotted on the <BR>\n" );
document.write( "horizontal axis<BR>\n" );
document.write( "The dependent variable is always plotted on the<BR>\n" );
document.write( "vertical axis<BR>\n" );
document.write( "-----------------------<BR>\n" );
document.write( "So, I want my equation to look like:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+G+=+f%28+D+%29+ ALIGN=MIDDLE  ALT=\"+G+=+f%28+D+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" >, so it is correct as shown:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+G+=+18+-+%28+1%2F20+%29%2AD+ ALIGN=MIDDLE  ALT=\"+G+=+18+-+%28+1%2F20+%29%2AD+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Here's the plot:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+graph%28+400%2C+400%2C+-50%2C+500%2C+-10%2C+22%2C+18+-+%28+1%2F20+%29%2Ax+%29+ ALIGN=MIDDLE  ALT=\"+graph%28+400%2C+400%2C+-50%2C+500%2C+-10%2C+22%2C+18+-+%28+1%2F20+%29%2Ax+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The graph looks OK<BR>\n" );
document.write( "If <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+D+=+0+ ALIGN=MIDDLE  ALT=\"+D+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" >, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+G+=+18+ ALIGN=MIDDLE  ALT=\"+G+=+18+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "If <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+D+=+360+ ALIGN=MIDDLE  ALT=\"+D+=+360+\"   DISABLED_style= \"max-width:90%; height:auto;\" >, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+g+=+0+ ALIGN=MIDDLE  ALT=\"+g+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );