Answer
$ a.\quad$ acceptable.
$ b.\quad$not acceptable.
Work Step by Step
a.
Does $x=214$ satisfy
$|x-220|\leq 8\quad ?$
$|214-220|=|-6|=6.$
Since $6\leq 8$, the voltage of $214$ Volts is acceptable.
b.
Does $x=209$ satisfy
$|x-220|\leq 8\quad ?$
$|209-220|=|-11|=11.$
So, the voltage of $209$ Volts is not acceptable.
