Explanation:
This is an arithmetic sequence. We know this because every term is simply one less than the term before it.
The explicit formula for an arithmetic sequence is aₙ = a₁ + (n-1)d, where a₁ is the first term and d is the common difference between consecutive terms. In this case, a₁ = 12 and d = -1.
Therefore, we have aₙ = 12 + (n - 1) · (-1) = 12 - n + 1 = -n + 13. aₙ = -n + 13.
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