Answer
Formula for $a_{n}$ term of the given sequence = $a_{1}$ + (n - 1) d.
Where
$a_{1}$ = The first term
d = Common difference
n = $n^{th}$ number of term
Given
$a_{1}$, the first term = 6
Common difference (d) = 3
$20^{th}$ term of sequence = 63
Work Step by Step
Formula for $a_{n}$ term of the given sequence = $a_{1}$ + (n - 1) d.
Where
$a_{1}$ = The first term
d = Common difference
n = $n^{th}$ number of term
Given
$a_{1}$, the first term = 6
Common difference (d) = 3
$20^{th}$ term of sequence = 6 + (20 - 1) $\times$ 3
= 6 + 19$\times$3
= 6 + 57
= 63
