document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=63631>Question 63631</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/093979862x/algebrahomeworkh>An Incremental Development</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> please help me to solve the following\r<BR>\n" );
document.write( "\n" );
document.write( "Use substitution to solve\r<BR>\n" );
document.write( "\n" );
document.write( "4x + y = 17 and 3x - 5y = 30 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #44379 by </B><A HREF=/tutors/aboutme.mpl?userid=funmath><B>funmath(2933)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=funmath><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=44379\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Use substitution to solve\r<BR>\n" );
document.write( "\n" );
document.write( "E1:  4x + y = 17 <BR>\n" );
document.write( "E2:  3x - 5y = 30<BR>\n" );
document.write( "Solve E1 for y and substitute it into E2 for y and solve for x.<BR>\n" );
document.write( "E1: -4x+4x+y=-4x+17 --> y=-4x+17<BR>\n" );
document.write( "E2: 3x-5(-4x+17)=30<BR>\n" );
document.write( "3x+20x-85=30<BR>\n" );
document.write( "23x-85=30<BR>\n" );
document.write( "23x-85+85=30+85<BR>\n" );
document.write( "23x=115<BR>\n" );
document.write( "23x/23=115/23<BR>\n" );
document.write( "x=5<BR>\n" );
document.write( "Substitute x=5 into E1 and solve for y:<BR>\n" );
document.write( "E1:  4(5)+y=17<BR>\n" );
document.write( "20+y=17<BR>\n" );
document.write( "-20+20+y=-20+17<BR>\n" );
document.write( "y=-3<BR>\n" );
document.write( "The solution: (x,y)=(5,-3)<BR>\n" );
document.write( "Check the solution by substituting 5 in for x and -3 in for y in both equations and see if the equations balance.<BR>\n" );
document.write( "E1:  4(5)+(-3)=17<BR>\n" );
document.write( "20-3=17<BR>\n" );
document.write( "17=17  E1 checks.<BR>\n" );
document.write( "E2: 3(5)-5(-3)=30<BR>\n" );
document.write( "15+15=30<BR>\n" );
document.write( "30=30  E2 also checks, so we know we're right!<BR>\n" );
document.write( "Happy Calculating!!! </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );