Answer:
x = 29
Explanation:
Focus on ΔDEC first. We know that two of its angles are ∠C = 48° and ∠D = 74°.
All of a triangle's angles must add up to 180° by the Triangle Sum Theorem. 48° + 74° = 122°. 180° - 122° is 58°. So ∠E is 58°.
Because the triangles are congruent, ∠E corresponds to ∠B.
Because ∠B is "2x," divide 58° by 2. 58° ÷ 2 = 29°. 29° × 2 = 58°, so this checks out.
I hope this helps!!