\"\"

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The given values \"\".

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Where \"\" is the first term and \"\" is the common difference.

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The sum of an arithmetic series \"\".

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\"\"            (Substitute \"\")

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\"\"                    (Add: 17 + 197 = 214)\"\"

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Apply multiplication property of equality: a = b then \"\".

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\"\"         (Multiply each side by 2)

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\"\"                 (Cancel common terms)

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

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Apply division property of equality: a = b then \"\".

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\"\"                      (Divide each side by 214)

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\"\"                               (Cancel common terms)

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

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Apply nth term of the arithmetic sequence formula: \"\".

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\"\"             (Substitute \"\")

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

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Apply subtraction property of equality: a = b then \"\".

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\"\"      (Subtract 17 from each side)

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\"\"          (Apply additive inverse property: \"\")

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\"\"                (Apply additive identity property: \"\")

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

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Apply division property of equality: a = b then \"\".

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\"\"                             (Divide each side by 20)

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\"\"                                    (Cancel common terms)

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d = 9                                           (Divide: \"\")

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The 1st term is \"\", 2nd term is \"\"

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3rd term is \"\"\"\"

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The first three terms of the arithmetic series is 17, 26, and 35.