In the figure below, C is on BD, ∠BAC measures 40°, and ∠ABC measures (June 2021 - D06)

Correct answer: E. 150°.
Reconsidering the problem: If line segment BC is extended towards point B (the opposite direction), it would create a different angle with AC. In this case, angle ACD would be part of an exterior angle of triangle ABC.

Exterior Angle Theorem: The exterior angle of a triangle is equal to the sum of the two remote interior angles of the triangle. In this case, the remote interior angles would be ∠BAC (40°) and ∠ABC (110°).

∠ACD = ∠BAC + ∠ABC
∠ACD = 40° + 110°
∠ACD = 150°