ABC with exterior angle 4 is given _____ = 180 degrees becaused the angles for a linear pair. This can be written as M angle 4 = 180 degrees - m angle 3 by the subtractions property of the quaulity since ____ = 108 degrees beause the the triangle sum theorem, this new equation can be written as M angle 4 = (m angle 1 + m angle 2 + m angle) - m angle 3 due to the _____ symplify the results in m angle 4 = m angle 1 + m angle 2. what are the missing parts of the proof? 3