document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=172805>Question 172805</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How do i slove the system 2x-5y=9 and -3x+y=-7 using the substitution method? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #127660 by </B><A HREF=/tutors/aboutme.mpl?userid=colliefan><B>colliefan(242)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=colliefan><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=127660\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Solve 2x-5y=9 and -3x+y=-7 using the substitution method:\r<BR>\n" );
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document.write( "Pick either equation and solve it for one variable, either variable will work. Let's say we're going to solve the second equation for y.\r<BR>\n" );
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document.write( "-3x+y=-7<BR>\n" );
document.write( "+3x-3x+y=-7+3x<BR>\n" );
document.write( "y=3x-7\r<BR>\n" );
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document.write( "Now, since y = 3x-7, we can replace y by 3x-7 in the other equation. That is why it is called the substitution method. We are substituting an expression from one equation into the other.<BR>\n" );
document.write( "2x-5(3x-7) = 9<BR>\n" );
document.write( "2x - 15x + (-5)(-7)  = 9<BR>\n" );
document.write( "-13x + 35 = 9<BR>\n" );
document.write( "-13x= -26<BR>\n" );
document.write( "x=2\r<BR>\n" );
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document.write( "Now that you know what x is, substitute it back into either equation and solve for y. Again, if you use the second equation:\r<BR>\n" );
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document.write( "-3x+y=-7<BR>\n" );
document.write( "-3(2)+y = -7<BR>\n" );
document.write( "-6 + y = -7<BR>\n" );
document.write( "y = -1\r<BR>\n" );
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document.write( "The solution we have calculated is x=2 and y=-1. Substitute these values into both equations to check to make sure this is a valid solution to the equations and you will see that this is the solution to these equations. </SPAN>\n" );
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