Answer:
Supplementary angles.
Step-by-step explanation:
We can define two big groups of pairs of angles.
Complementary and supplementary angles.
Two angles are complementary if the sum of their measures is equal to 90°
Two angles are supplementary if the sum of their measures is equal to 180°
Here, we have the angles 160° and 20°, and we know that their sum is 180°
Then we can conclude that the given angles fall in the group of the supplementary angles.
