Chapter 1, Equations and Inequalities - 1.7 Solve Absolute Value Equations and Inequalities - 1.7 Exercises - Skill Practice - Page 55: 27

$$j=-7\quad \mathrm{or}\quad \:j=2$$

Since the value inside the absolute value can be positive or negative and get the same number, we must consider both options. Doing this, we find: $$5+2j=-9\quad \mathrm{or}\quad \:5+2j=9 \\ j=-7\quad \mathrm{or}\quad \:j=2$$