Answer:
55°
Step-by-step explanation:
1. As you can see, this is an isosceles triangle because two sides are congruent. The two angles that oppose these two marked sides are also congruent.
2. The angle that opposes Side EF is ∠D, 55°, and the angle that opposes Side ED is ∠F, y. Because these two angles are congruent, y = 55°.
