Answer
$a_{n}=6n$
$a_{30}=180$
Work Step by Step
The first term is $6$ and the common difference is $12-6=6$.
Equation for an arithmetic sequence is
$a_{n}=a_{1}+(n-1)d $
where $a_{1}$ is the first term and $d$ is the common difference.
$a_{n}=6+(n-1)(6)$
$a_{n}=6+6n-6=6n$
$a_{30}=6(30)=180$
