\"\"

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Slope of the two non vertical lines is \"\".

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The y-coordinate are same. So, the line is y = -3. The line is horizontal line.

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So, slope is zero.\"\"

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Check the solution by substituting the values.

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Replace \"\" in slope formula.

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\"\"

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\"\"                             (Subtract:\"\")

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\"\"                                  (Subtract: \"\")

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\"\"                                    (Divide: \"\")\"\"

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The slope is zero.