Question

Angle sum theorem
25°
30°

Answer 1

y = 55°

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°

Answer 2

x = 125°

y = 180-125 = 55°

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°