How do you find the degree of a missing angle to a quadraleral when given only the degrees of 2 angles?

Got this from googleSubtract the sum of the angles from 180 degrees to get the missing angle. For example if a triangle in a quadrilateral had the angles of 30 and 50 degrees, you would have a third angle equal to 100 degrees (180 - 80 = 100).Hope this helps!