$\"\"$

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The expression is $\"\"$ .

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$\"\"$ (Combination formula)

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

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Expand the factorial: $\"\"$ .

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$\"\"$

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$\"\"$ (Cancel common terms) $\"\"$

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Multiply: $\"\"$ .

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$\"\"$

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

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$\"\"$ (Multiply: $\"\"$ ) $\"\"$

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The value of $\"\"$ is $\"\"$ .