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

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The expression is \"\"

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\"\"  (Evaluate power: \"\")

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\"\"    (Evaluate power: \"\")

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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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According to subtraction Property of equality: If \"\", then \"\".

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\"\"                    (Subtract 3b from each side)

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

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

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

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\"\"                                (Divide each side by 21) \ \

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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.