Answer:
(an -a1)/d +1 = n
Step-by-step explanation:
Undo what is done to n, in reverse order. When evaluating this expression, you ...
When you undo these, you get ...
... an -a1 = d(n-1) . . . . . . subtract a1
... (an -a1)/d = n - 1 . . . . divide by d
... (an -a1)/d +1 = n . . . . add 1
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Comment on answer list
Please note the use of parentheses in the answer here. These identify that the difference (an -a1) is what is divided by d. None of the offered answers has these parentheses, nor are they typeset in a way that would indicate the intent to divide (an -a1) by d. As given, none of the offered answers is correct.
