Find the sum of the first twenty-seven terms of an arithmetic series whose first term is -8 and the sum of the first seven term is 28.

answer: i don't understand. what are the options

step-by-step explanation:

step by step solution :

step   1   :

1.1     4 = 22

(4)3 = (22)3 = 26

equation at the end of step   1   :

  ((23) • 26)2

step   2   :

equation at the end of step   2   :

  (23 • 26)2

step   3   :

final result :

  218

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