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 = (-70)
Common difference (d) = (-5)
$20^{th}$ term of sequence = -165
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 = (-70)
Common difference (d) = (-5)
$20^{th}$ term of sequence = -70 + (20 - 1) $\times$ (-5)
= -70 + 19$\times$(-5)
= -70 -95
= -165
