What is the sum of angles that are classified as supplementary?

Supplementary angles are defined as two angles whose measures add up to exactly 180 degrees. This classification is a fundamental concept in geometry, emphasizing the relationship between angles when they are combined.

For example, if one angle measures 120 degrees, the supplementary angle would measure 60 degrees, since 120 + 60 = 180. Thus, the sum of any such pair of angles will consistently amount to 180 degrees, identifying them as supplementary.

The other provided options do not align with the definition of supplementary angles. The sum of 360 degrees pertains to angles that make a full rotation, 90 degrees corresponds to complementary angles, and the combination of 180 and 360 degrees introduces angles that do not directly relate to the strict definition of supplementary angles. Hence, the only option that correctly reflects the sum of supplementary angles is 180 degrees.