$\"\"$ $\"\"$ $\"\"$

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

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Replace $\"\"$ in slope formula.

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$\"\"$

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

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Apply multiplication property of equality: Multiply each side by 3.

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$\"\"$

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$\"\"$ (Cancel common terms)

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Apply subtraction property of equality: Subtract 4 from each side.

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$\"\"$

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Rearrange the terms using commutative property of addition: a+b = b+a.

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$\"\"$

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

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$\"\"$ (Cancel common signs) $\"\"$

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Check:

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To check the solution, substitute $\"\"$ in original equation.

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$\"\"$

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

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

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Compare the values, the equation is true. $\"\"$

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The value of $\"\"$ .