$\"\"$

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The proportion is $\"\"$ .

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Apply cross product property: If $\"\"$ , where $\"\"$ .

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$\"\"$

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$\"\"$ (Apply distributive property: $\"\"$ )

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

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$\"\"$ (Subtract 20 from each side)

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

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

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

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$\"\"$ (Divide each side by 4)

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$\"\"$ (Cancel common terms)

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

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The solution is $\"\"$ .