$\"\"$

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The expression is $\"\"$ of 25.

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Fraction method:

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81 is about 80.

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Think $\"\"$ .

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The expression can be $\"\"$ of 25.

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$\"\"$

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$\"\"$ (Think: $\"\"$ )

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$\"\"$ (Think: $\"\"$ ) $\"\"$

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Using Fraction method, 20 is $\"\"$ of 25.