Answer
$a_n=81-7n$
Work Step by Step
Let $a_n$ be our arithmetic sequence. We are given:
$$\begin{align*}
a_{12}&=-3\\
d&=-7.
\end{align*}$$
We determine the first term $a_1$:
$$\begin{align*}
a_n&=a_1+(n-1)d\\
a_{12}&=a_1+(12-1)d\\
-3&=a_1+11(-7)\\
-3+77&=a_1\\
a_1&=74.
\end{align*}$$
We write the rule for the general term $a_n$:
$$\begin{align*}
a_n&=a_1+(n-1)d\\
a_n&=74+(n-1)(-7)=74-7n+7=81-7n.
\end{align*}$$
We got:
$$a_n=81-7n.\tag1$$
We calculate the first six terms substituting $n=2,3,4,5,6$ in Eq. $(1)$ and $a_1=74$:
$$\begin{align*}
a_1&=74\\
a_2&=81-7(2)=67\\
a_3&=81-7(3)=60\\
a_4&=81-7(4)=53\\
a_5&=81-7(5)=46\\
a_6&=81-7(6)=39.
\end{align*}$$
Graph the first six terms:
