Ease Into Prep with an SAT^® Question of the Day

By definition, |x| indicates the distance of x from 0. Thus, |x| = 4 says that x is 4 units from 0. That is, x = 4 or x = −4. Since c and d are 4 units from a, then the coordinates of c and d are x = a + 4 and x = a − 4. Subtracting a from both sides gives x − a = 4 and x − a = −4, which can be written more concisely as |x − a| = 4. (B) is correct.