You can put this solution on YOUR website! I haven't heard of the "y = y method."
Maybe you solve both eqns for y, then go from there?
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2x + y = 12 --> y = 12-2x
3x – y = 8 --> y = 3x-8
Then they equal each other?
12-2x = 3x-8
5x = 20
x = 4
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y = 4
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Is that it?
Some call that substitution.