document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1190990>Question 1190990</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Solve this system of linear equations using substitution: x - 7y = -11; and 5x + 2y = -18 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #822743 by </B><A HREF=/tutors/aboutme.mpl?userid=math_tutor2020><B>math_tutor2020(3817)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=math_tutor2020><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=822743\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font color=black size=3><BR>\n" );
document.write( "Let's solve the first equation for x<BR>\n" );
document.write( "x - 7y = -11<BR>\n" );
document.write( "x = -11 + 7y\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "We'll then plug this into the other equation.<BR>\n" );
document.write( "Wherever you see an x, replace it with (-11+7y)<BR>\n" );
document.write( "The term \"substitute\" effectively means \"replace\".<BR>\n" );
document.write( "So,<BR>\n" );
document.write( "5x + 2y = -18<BR>\n" );
document.write( "5(-11+7y) + 2y = -18<BR>\n" );
document.write( "-55+35y + 2y = -18<BR>\n" );
document.write( "-55+37y = -18<BR>\n" );
document.write( "37y = -18+55<BR>\n" );
document.write( "37y = 37<BR>\n" );
document.write( "y = 37/37<BR>\n" );
document.write( "y = 1\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "We can now find x based on that<BR>\n" );
document.write( "x = -11+7y<BR>\n" );
document.write( "x = -11+7(1)<BR>\n" );
document.write( "x = -11+7<BR>\n" );
document.write( "x = -4\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<font color=red>Solution: x = -4 and y = 1</font>\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "-------------------------------<BR>\n" );
document.write( "Check:\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Plug x = -4 and y = 1 into the first original equation<BR>\n" );
document.write( "x-7y = -11<BR>\n" );
document.write( "-4-7(1) = -11<BR>\n" );
document.write( "-4-7 = -11<BR>\n" );
document.write( "-11 = -11\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Repeat for the other original equation as well<BR>\n" );
document.write( "5x + 2y = -18<BR>\n" );
document.write( "5(-4) + 2(1) = -18<BR>\n" );
document.write( "-20 + 2 = -18<BR>\n" );
document.write( "-18 = -18<BR>\n" );
document.write( "For each equation above, we get a true statement (i.e. the same number on both sides).<BR>\n" );
document.write( "The solution is fully confirmed.<BR>\n" );
document.write( "</font><BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );