The answer is 100
Explaination
The side angles in the bottom right triangle has 2 sides that are 50 degrees, wich means the other side is 80 since a triangle equals 180 degrees.
50+ 50 + 80 is 180 so this is correct.
A straight line is also 180.
Since this straight line is being intersected, and one side of the intersection is 80, we can subtract 180 by 80
180-80= 100
100 is your answer