document.write( "Question 301316: How do you solve: using substitution
\n" ); document.write( "5x-2y=-7
\n" ); document.write( "8=y-4x \n" ); document.write( "

Algebra.Com's Answer #216050 by Stitch(470) $\"\"$ $\"About$

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Set-Up:
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\n" ); document.write( "Equation 1: $\"5X+-+2Y+=+-7\"$
\n" ); document.write( "Equation 2: $\"8+=+Y+-+4X\"$
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\n" ); document.write( "Solution:
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\n" ); document.write( "You need to solve one of the equations for one variable. in this case I thin that solving equation 2 for Y is the easiest.
\n" ); document.write( "Equation 2: $\"8+=+Y+-+4X\"$ Add 4X to both sides
\n" ); document.write( " $\"8+%2B+4X+=+Y\"$
\n" ); document.write( "Now you can plug (8 + 4X) into equation 1 for Y
\n" ); document.write( "Equation 1: $\"5X+-+2Y+=+-7\"$
\n" ); document.write( " $\"5X+-+2%2A%288+%2B+4X%29+=+-7\"$ Simplify
\n" ); document.write( " $\"5X+-+16+-+8X+=+-7\"$ Simplify
\n" ); document.write( " $\"-3X+-+16+=+-7\"$ Add 16 to both sides
\n" ); document.write( " $\"-3X+=+9\"$ Divide both sides by -3
\n" ); document.write( " $\"highlight%28X+=+-3%29\"$
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\n" ); document.write( "Now plug -3 into equation 2 for X
\n" ); document.write( " $\"8+%2B+4X+=+Y\"$
\n" ); document.write( " $\"8+%2B+4%2A%28-3%29+=+Y\"$
\n" ); document.write( " $\"8+-+12+=+Y\"$
\n" ); document.write( " $\"highlight_green%28-4+=+Y%29\"$
\n" ); document.write( " \n" ); document.write( "

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