Tyler Wallace's "Beginning and Intermediate Algebra: Section 1.6: Solving Linear Equations - Absolute Value"
Read this section. The equations x - 3 = 2 and |x - 3| = 2 are very different from each other, but they are also closely. Notice how we turn an equation with absolute values into two equations without absolute values. Note that this reading covers all the material you need to know for subunits 1.5.1-1.5.3.