Answer
The sequence is arithmetic.
Common difference: $-3$
The general term: $a_{n}=-3n+85$
Work Step by Step
$a_{2}-a_{1}=79-82=-3$
$a_{3}-a_{2}=76-79=-3$
$a_{4}-a_{3}=73-76=-3$
$a_{5}-a_{4}=70-73=-3$
$a_{6}-a_{5}=67-70=-3$
As the difference between each term and the preceding term is the same, the sequence is arithmetic.
The general term is
$a_{n}=a_{1}+(n-1)d$
where $d$ is the common difference.
$a_{1}=82$, $d=-3$
$\implies a_{n}=82+(n-1)(-3)$
Or $a_{n}=82-3n+3=-3n+85$
