Answer:
∠ ACD = 140°
Step-by-step explanation:
Since ∠ DCE and ∠ DEC are congruent , then
∠ DCE = [tex]\frac{180-100}{2}[/tex] = [tex]\frac{80}{2}[/tex] = 40°
∠ ACD and ∠ DCE are adjacent and supplementary, that is sum to 180°
∠ ACD = 180° - ∠ DCE = 180° - 40° = 140°
