Answer:
107
Step-by-step explanation:
EFD + 135 = 180
EFD = 45
DEF + 28 + 45 = 180
DEF + 73 = 180
DEF = 107
∠ DEF = 107°
The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
135° is an exterior angle of the triangle , then
∠ DEF + 28° = 135° ( subtract 28° from both sides )
