a(n) = 17-5(n)
If n = 1 then a(1) = 17-5(1) = 17-5 = 12, so the first term would be 12
If n = 2 then a(2) = 17-5(2) = 17-10 = 7
The difference would be a(1) - a(2) = 12 - 7 = 5
So the recursive formula would be an = a(n-1) + 5 and the first term was 12, so the answer would be A.
