Answer: B. p + q + r = 180 degrees
Step-by-step explanation:
We know that for any triangle one relationship is always correct between the angles of the triangle, i.e the sum of all the interior angles of a triangle is 180°.
Therefore, if triangle ABC has angle ABC labeled as q, angle BCA labeled as r, and the exterior angle at A labeled as p.
Then p + q + r = 180 degrees [By angle sum property of triangle]
