Exercise 18 Page 394

Let's start by recalling the definitions of complementary and supplementary angles.

Complementary Angles	Supplementary Angles
Two angles are complementary if the sum of their measures is 90^(∘).	Two angles are supplementary if the sum of their measures is 180^(∘).

Let's now consider the given angles.

To determine whether they are complementary, supplementary, or neither, we will calculate the sum of their measures. 59^(∘) + 31^(∘) = 90^(∘) Since the sum equals 90^(∘), the angles are complementary.