Find an equation for the nth term of the arithmetic sequence.

-20, - 16, - 12, - 8,.

We are given with the sequence - 20, - 16, - 12, - 8. From this sequence, we can see that the arithmetic difference is + 4, from - (-20 + 16). hence following the arithmetic formula of an = a1 + d * (n-1). Substituting, an = - 20 + 4 * (n-1) where n is an integer