Angle sum theorem
25°
30°

Answer:
x = 125°
y = 180-125 = 55°
Step-by-step explanation:
The angles should sum to 180 in a triangle.
Since the other two are 25 and 30, for the third one, 180-25-30 = 125 is left, which is x.
Now y and x are supplementary angles, which means that x+y is also 180°.
So y = 180-x = 55°
Answer:
y = 55°
Step-by-step explanation:
The external angle of a triangle is equal to the sum of the 2 opposite interior angles.
y is an exterior angle of the triangle, thus
y = 25° + 30° = 55°