$\"\"$

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The equation is $\"\"$ .

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Subtract 21 from each side.

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$\"\"$

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$\"\"$

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$\"\"$ can be written as $\"\"$ .

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$\"\"$

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Take out common factor.

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$\"\"$

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$\"\"$

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Apply zero product property: ab = 0 then a = 0 and b = 0.

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$\"\"$ $\"\"$

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$\"\"$

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Subtract 7 from each side.

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Add 3 to each side.

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$\"\"$

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$\"\"$

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Divide each side by 2.

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$\"\"$

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$\"\"$

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$\"\"$

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The factors is $\"\"$ .