$\"\"$

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The proportion is $\"\"$ .

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

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$\"\"$ (Cross products)

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

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

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

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Apply addition property of equality: Add 50 to each side.

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$\"\"$

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

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

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Apply division property of equality: Divide each side by 10.

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$\"\"$

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$\"\"$ (Cancel common terms)

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

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The value of $\"\"$ .