\"\"

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Let \"\",\"\",\"\"and \"\".

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\"\"              (Segment products)

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\"\"                        (Substitute \"\",\"\",\"\"and \"\")

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\"\"                            (Multiply: \"\")

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\"\"                       (Divide each side by 9)

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\"\"                            (Cacel common terms)

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

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The value of \"\".