All of the angles in a triangle add up to 180°.

The missing angle is 146°
Answer: I got A. 768 as the answer
<4 ≅ <1, 3 <≅ 2 Corresponding angles postulate
ΔACE ≈ ΔBCD Angle angle similarity postulate
(CB + BA)/CB = (CD + DE)/CD Substitution property of equality