Answer
(a) $|x-0.020|\leq 0.003$
(b) $0.017\leq x\leq 0.023$
Work Step by Step
(a) If $x$ is the thickness of the laminate, then:
$|x-0.020|\leq 0.003$
Since $0.003$ represents the "error" or tolerance from the goal of $0.020$.
(b)
$|x-0.020|\leq 0.003$
$-0.003\leq x-0.020\leq 0.003$
$ 0.017\leq x\leq 0.023$