Appendix I - A Symbols, Arithmetic Operations, Exponents, and Scientific Notation - Commonly Used Symbols in Relationships - Appendix I-A Exercises on Symbol Usage - Page A-1: 1

Any x between +3 and +8 and any x between -3 and -8 (both end values of each interval included)

Since $3\leq|x|\leq8$, x must be such that $3\leq x\leq 8$ and $-8 \leq x \leq -3$. So, value of x has to be such that x is between +3 and +8 or between -3 and -8 (both end values of each interval included)