Answer:
x = 70
Step-by-step explanation:
The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
z is ab exterior angle of the triangle , then
x + y = z , that is
x + x - 15 = 125
2x - 15 = 125 ( add 15 to both sides )
2x = 140 ( divide both sides by 2 )
x = 70
