document.write( "Question 1007830: I need to solve this equation using substitution
\n" ); document.write( "-x-y-z=-8
\n" ); document.write( "-4x+4y+5z=7
\n" ); document.write( "2x+2z=4
\n" ); document.write( "i am confused.Thank you for your help \n" ); document.write( "
Algebra.Com's Answer #623664 by Alan3354(69443)\"\" \"About 
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I need to solve this equation using substitution
\n" ); document.write( "-x-y-z=-8
\n" ); document.write( "-4x+4y+5z=7
\n" ); document.write( "2x+2z=4
\n" ); document.write( "===================
\n" ); document.write( "It's not just an equation. It's 3 equations, a system of equations.
\n" ); document.write( "---
\n" ); document.write( "-x-y-z=-8
\n" ); document.write( "-4x+4y+5z=7
\n" ); document.write( "2x+2z=4 --> x + z = 2 --> z = 2 - x
\n" ); document.write( "-----
\n" ); document.write( "Sub for z in the 1st 2 equations.
\n" ); document.write( "-x-y- (2-x) = -8
\n" ); document.write( "-x-y -2+x = -8
\n" ); document.write( "-y-2 = -8
\n" ); document.write( "y = 6
\n" ); document.write( "==================
\n" ); document.write( "-4x+4y+5z=7
\n" ); document.write( "Sub for y & z
\n" ); document.write( "-4x + 4*6 + 5(2-x) = 7
\n" ); document.write( "-4x + 24 + 10 - 2x = 7
\n" ); document.write( "-6x = -27
\n" ); document.write( "x = 9/2
\n" ); document.write( "=================
\n" ); document.write( "z = 2 - x
\n" ); document.write( "x = -5/2
\n" ); document.write( "=============== \n" ); document.write( "
\n" );