\"\"\"\"\"\"

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The expression is \"\"

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\"\"   (Evaluate powers: \"\")

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\"\"    (Evaluate powers: \"\")

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\"\"      (Multiply: \"\")

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

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

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\"\"

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Apply subtraction Property of equality: Subtract 3b from each side.

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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 21.

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\"\"

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\"\"                                (Cancel common terms)

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

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\"\"

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The value of b is 0.