Answer:
159°
Step-by-step explanation:
We can calculate supplementary angles by subtracting the given one angle from 180 degrees. To find the other angle, use the following formula: ∠x = 180° – ∠y or ∠y = 180° – ∠x where ∠x or ∠y is the given angle.
so 180° – ∠ 21= 159°
