Step-by-step explanation:
The Triangle Sum Theorem states that if you add all three interior angles, those are the angles inside the triangle, they would add up to 180 degrees. It is easy to remember that we add the three angle measurements to get 180 degrees because of the word sum in the name of the theorem. To make it short and sweet: a + b + c = 180°
In our problem, we need to determine the third angle measurement. To find this angle measurement, all we have to do is subtract the two angle measurements that we have from 180 degrees. So, we have the following: