$\"\"$

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The equation is $\"\"$ .

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Solve the equation $\"\"$ for c.

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Multiply each side by $\"\"$ .

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$\"\"$

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$\"\"$ . $\"\"$

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Add 18 to each side.

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ . $\"\"$

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The value of $\"\"$ .