$|x-0| \leq 3.5$
The inequality represents all real numbers $x$ with distance from $0$ that is less than or equal to $3.5$, so $|x-0| \leq 3.5$ means the same as the compound inequality $-3.5 \leq x-0 \leq 3.5$$-3.5 \leq x-0 \leq 3.5$
Removing $0$ doesn't change the value, so remove it from the expression$\begin{align*}&-3.5 \leq x \leq 3.5 \\&\begin{array} { l }x \in \left[ -3.5, 3.5\right]\end{array}\end{align*}$