\"\"

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

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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 40 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 subtraction property of equality: Subtract 15n from each side.

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\"\"

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Apply commutative property of addition: a + b = b + a.

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\"\"

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

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

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Apply division property of equality: Divide each side by 5.

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\"\"

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\"\"                                      (Cancel common terms)

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

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The value of \"\".