document.write( "Question 75571: 50.Solve the system by substitution.
\n" ); document.write( " 3x + 3y = 9
\n" ); document.write( " y = 2x – 12\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

Algebra.Com's Answer #54213 by jim_thompson5910(35256) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"3x+%2B+3y+=+9\"$
\n" ); document.write( " $\"y+=+2x+-+12\"$ Plug this equation into the first one\r
\n" ); document.write( "\n" ); document.write( " $\"3x+%2B+3%2A%28highlight%282x-12%29%29+=+9\"$ Substitute 2x-12 into y
\n" ); document.write( " $\"3x%2B6x-36=9\"$ Distribute the 3
\n" ); document.write( " $\"9x-36=9\"$ Combine like terms
\n" ); document.write( " $\"9x=45\"$ Add 36 to both sides
\n" ); document.write( " $\"x=5\"$ Divide both sides by 9\r
\n" ); document.write( "\n" ); document.write( "Use this to find y.
\n" ); document.write( " $\"3%285%29+%2B+3y+=+9\"$
\n" ); document.write( " $\"15+%2B+3y+=+9\"$ Multiply
\n" ); document.write( " $\"3y+=+-6\"$ Subtract 15 from both sides
\n" ); document.write( " $\"y+=+-2\"$ Divide both sides by 3
\n" ); document.write( "So the solution is (5,-2)
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\n" ); document.write( "Check:
\n" ); document.write( " $\"3%285%29+%2B+3%28-2%29+=+9\"$ plug in (5,-2)
\n" ); document.write( " $\"-2+=+2%285%29+-+12\"$
\n" ); document.write( " $\"15+-6+=+9\"$
\n" ); document.write( " $\"-2+=+10+-+12\"$
\n" ); document.write( " $\"9+=+9\"$ works
\n" ); document.write( " $\"-2+=+-2\"$ works
\n" ); document.write( "So the solution satisfies the system \n" ); document.write( "

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