document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=62783>Question 62783</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Can you please help me solve by using the subtitution and elimination method (unless there is no infnite number or solution.)  <BR>\n" );
document.write( "y = 4 - x,<BR>\n" );
document.write( "3x + 4y = 21  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #43617 by </B><A HREF=/tutors/aboutme.mpl?userid=jai_kos><B>jai_kos(139)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jai_kos><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=43617\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "Given<BR>\n" );
document.write( "y = 4 - x --->(1)<BR>\n" );
document.write( "3x + 4y = 21 --->(2)\r<BR>\n" );
document.write( "\n" );
document.write( "Now substitue equation(1) in (2), we get\r<BR>\n" );
document.write( "\n" );
document.write( "3x+ 4(4-x) = 21\r<BR>\n" );
document.write( "\n" );
document.write( "3x + 16 -4x= 21 \r<BR>\n" );
document.write( "\n" );
document.write( "16 -x = 21\r<BR>\n" );
document.write( "\n" );
document.write( "Get all the numbers on one side, we get\r<BR>\n" );
document.write( "\n" );
document.write( "16 -21 = x\r<BR>\n" );
document.write( "\n" );
document.write( "-5 = x\r<BR>\n" );
document.write( "\n" );
document.write( "Now substitue for x =-5 in equation(1), we get\r<BR>\n" );
document.write( "\n" );
document.write( "y = 4 -(-5) = 4 + 5 = 9\r<BR>\n" );
document.write( "\n" );
document.write( "Hence the value of x = -5 and y = 9 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );