$\"\"$

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The points are $\"\"$ .

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Let $\"\"$

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(Apply formula: $\"\"$ )

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$\"\"$ (Substitute the points) $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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The three points are collinear so $\"\"$ .

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$\"\"$ (Subtract 9 from each side)

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$\"\"$

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$\"\"$ (Divide each side by negative 3) $\"\"$

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The value of the y = 3.