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

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The equation is $\"\"$ .

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Write two cases:

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Case-1: a = b

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$\"\"$

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Case-2: a = $\"\"$ b

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

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Solve the equation for Case-2.

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According to subtraction property of equality: if $\"\"$ , then $\"\"$ .

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$\"\"$ (Subtract 12 from each side)

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

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

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Check:

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To check the solution, substitute $\"\"$ in original equation.

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$\"\"$

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$\"\"$ (Add: 21 + 12 = 33)

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33 = 33 (Absolute value: |33| = 33)

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Compare the values the equation is true. $\"\"$ is a solution.

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$\"\"$

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Solve the equation for Case-2.

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According to subtraction property of equality: if $\"\"$ , then $\"\"$ .

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$\"\"$ (Subtract 12 from each side)

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

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

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Check:

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To check the solution, substitute $\"\"$ in original equation.

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$\"\"$

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

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$\"\"$ (Absolute value: | $\"\"$ 33| = 33)

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Compare the values the equation is true. $\"\"$ is a solution.

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$\"\"$

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The solutions are 21 and $\"\"$ . The solution set is $\"\"$ .