Answer:
Their sum is 140. The measure of an exterior angle is supplementary to the respective interior angle.
Explanation:
Since the angle are on a straight line, m2 and 140 sum to 180.
So m2=40. Because a triangle has 180 degrees, m1 and m3 must sum to 140.
The exterior angle is always on the same incline as the interior angle, so it is always supplementary to the interior angle.