document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1176261>Question 1176261</A>: <I><SPAN STYLE=\"word-break: break-all;\"> You and your friends go out to lunch. Sandwiches cost $7 each and drinks cost $2 each. You buy a total of 10 items for lunch and spend a total of $40. Write a system of linear equations that describes this situation. Find the solution. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #802737 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=802737\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "Since they want a system of linear equations, we will use two variables.<br><BR>\n" );
document.write( "x = number of sandwiches<BR>\n" );
document.write( "y = number of drinks<br><BR>\n" );
document.write( "7x = cost of the sandwiches at $7 each<BR>\n" );
document.write( "2y = cost of the drinks at $2 each<br><BR>\n" );
document.write( "The total number of items is 10:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%2By+=+10 ALIGN=MIDDLE  ALT=\"x%2By+=+10\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "The total cost is $40:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7x%2B2y+=+40 ALIGN=MIDDLE  ALT=\"7x%2B2y+=+40\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "Double the first equation and compare it to the second:<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7x%2B2y+=+40 ALIGN=MIDDLE  ALT=\"7x%2B2y+=+40\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2x%2B2y+=+20 ALIGN=MIDDLE  ALT=\"2x%2B2y+=+20\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "The difference is<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5x+=+20 ALIGN=MIDDLE  ALT=\"5x+=+20\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+4 ALIGN=MIDDLE  ALT=\"x+=+4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "The number of sandwiches ordered was x=4.<br><BR>\n" );
document.write( "Informally, that means the number of drinks was 10-4 = 6.<br><BR>\n" );
document.write( "Formally....<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2By+=+10 ALIGN=MIDDLE  ALT=\"4%2By+=+10\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+10-4+=+6 ALIGN=MIDDLE  ALT=\"y+=+10-4+=+6\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );