Answer
The sequence is the arithmetic sequence.
Common difference is $-6$.
Work Step by Step
The given sequence is
$-20,-26,-32,-38,...$
Calculate difference between consecutive terms.
$-26-(-20)=-26+20=-6$
$-32-(-26)=-32+26=-6$
$-38-(-32)=-38+32=-6$
Consecutive terms have common difference of $-6$.
So, the sequence is the arithmetic sequence.
