$\"\"$

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The equation is $\"\"$ .

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$\"\"$ (Write the equation)

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$\"\"$ (Apply commutative law of addition: $\"\"$ )

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$\"\"$ (Add: $\"\"$ )

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Apply subtraction property of equality: if $\"\"$ .

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

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$\"\"$ (Apply additive inverse property: $\"\"$ )

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$\"\"$ (Apply additive identity property: $\"\"$ )

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

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Check whether $\"\"$ is a solution.

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$\"\"$ (Write the equation)

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Add: $\"\"$ )

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$\"\"$ is a solution. $\"\"$

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The solution is $\"\"$ .