Answer:
f(x)=12-5(n-1)
Step-by-step explanation:
Let's look at the options.
The last 2 options both represent a geometric sequence, so that cannot be the answer.
Now, notice that the common difference between the terms in the sequence is -5. The first option suggests that that it is 5, while the second suggests that it is -5, so the second option is the correct one.
