Answer:
107 degrees
Explanation:
The external angle (135 degrees) and the 2 farthest angles away from it (added together) are congruent to one another. The 2 farthest angles would be Angle D and Angle E. In this case we need to find Angle E.
All you need to do is subtract 28 from 135 (the external angle):
135 - 28 = 107
So, Angle DEF = 107 degrees.