Answer:
x = a + b
Explanation:
This is a proof
Exterior angle of a triangle = Sum of Interior and opposite angles
Exterior angle of a triangle = x
Sum of Interior and opposite angles = a + b
know that
a + b + c = 180 ______1 (total sum of angles in a triangle)
x + c = 180 _______2 (total sum of angles on a straight line)
from equation 1
c = 180 - (a + b)
from equation 2
c = 180 - x
hence
180 - (a + b) = 180 - x
180 - 180 + x = a + b
x = a + b