Answer:
15°, 15° , 150°
Explanation:
The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
2y + 20 is an exterior angle of the triangle , then
2y + 20 = 2y + 5 + y + 10
2y + 20 = 3y + 15 ( subtract 3y from both sides )
- y + 20 = 15 ( subtract 20 from both sides )
- y = - 5 ( multiply both sides by - 1 )
y = 5
Then
∠ A = 2y + 5 = 2(5) + 5 = 10 + 5 = 15°
∠ B = y + 10 = 5 + 10 = 15°
∠ C = 180° - 15° - 15° ( sum of angles in Δ = 180° )
∠ C = 180° - 30° = 150°