Question 334394
Absolute Value Inequalities are on the form:
|x| < a

From the question we have the inequality:
3.5 &#8804; x &#8804; 21

We must transform this, and the first step is to get the same abs value on each side. We can do this by subtracting (21 + 3.5) / 2 = 12.25 from each side:
(3.5 - 12.25) &#8804; (x - 12.25) &#8804; (21 - 12.25)
-8.75 &#8804; (x - 12.25) &#8804; 8.75
|x - 12.25| &#8804; 8.75