$\"\"$

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The expression is $\"\"$ .

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Add the polynomials horizontally

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$\"\"$ (Remove brackets)

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

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

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

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The sum of polynomials is $\"\"$ .