Answer:
m + n = 140°
Step-by-step explanation:
∵ The measure of the angle next to n = 40° ⇒ vertically opposite angle with the angle 40°
From parallel lines m , n and angle 40° next to n are interior supplementary means their sum is 180°
∴ m + n + 40° = 180°
∴ m + n = 180 - 40 = 140°
