Answer
This is an arithmetic sequence. The common difference, $d$, is $11$.
Work Step by Step
Let's look at the terms to see if we can find a pattern:
$a _2 - a_1 = 22 - 11 = 11$
$a_3 - a_2 = 33 - 22 = 11$
$a_4 - a_3 = 44 - 33= 11$
This is an arithmetic sequence because the same number is added to the previous term to get the next term, which means there is a common difference, and that difference $d$ is $11$.
