Answer:
x = 90
Explanation:
Here 60 is angle B, 30 is Angle a, B is The third angle of the triangle, and x is the exterior angle measurement!
60 + 30 + b= 180
a + x = 180
60 + 30 + b= 180
90 + b = 180
b = 90
90 + x = 180
x = 90
Note:
exterior angle equal to the sum of its two opposite non-adjacent interior angles.