Concept:Angles on a straight line sum to 180°. The three interior angles of a triangle sum to 180°.Explanation:First, find the angle linear to 156°. That is ∠x = 180° – 156° = 24°. Next, find the angle linear to 64°. That is ∠y = 180° – 64° = 116°. Now, ∠x, ∠y, and ∠z are the three interior angles of the triangle. Their sum is 180°. So, ∠z = 180° – ∠x – ∠y = 180° – 24° – 116° = 40°.Answer:C. 40°
