document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=43849>Question 43849</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Solve the system by substitution.\r<BR>\n" );
document.write( "\n" );
document.write( "x + y = -7\r<BR>\n" );
document.write( "\n" );
document.write( "x - y = 13  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #28864 by </B><A HREF=/tutors/aboutme.mpl?userid=adamchapman><B>adamchapman(301)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=adamchapman><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=28864\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> x+y=-7      ..1<BR>\n" );
document.write( "x-y=13      ..2<BR>\n" );
document.write( "rearrange equation(..2) to give:<BR>\n" );
document.write( "y=x-13      ..3<BR>\n" );
document.write( "now substitute equation (..3) into equation (..1) for y:<BR>\n" );
document.write( "x+(x-13)=-7<BR>\n" );
document.write( "2x-13=-7<BR>\n" );
document.write( "2x=6<BR>\n" );
document.write( "x=3         ..4<BR>\n" );
document.write( "now substitute equation (..4) into equation (..3) for y:<BR>\n" );
document.write( "y=3-13<BR>\n" );
document.write( "y=-10\r<BR>\n" );
document.write( "\n" );
document.write( "Therefore x=3 and y=-10\r<BR>\n" );
document.write( "\n" );
document.write( "I hope this helps. If you have any other problems, please dont hesitate to contact me at adam.chapman@student.manchester.ac.uk </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );