Answer:
a = 25° , b = 125°
Explanation:
the exterior angle of a triangle is equal to the sum of the 2 opposite interior angles
55° is an exterior angle of the triangle , then
a + 30° = 55° ( subtract 30° from both sides )
a = 25°
b and 55° are a linear pair and sum to 180° , that is
b + 55° = 180° ( subtract 55° from both sides )
b = 125°