Answer:
see explanation
Step-by-step explanation:
The exterior angle of a triangle is equal to the sum of the 2 opposite interior angle.
146° is an exterior angle of the triangle, then
5y + 3 + 4y + 8 = 146
9y + 11 = 146 ( subtract 11 from both sides )
9y = 135 ( divide both sides by 9 )
y = 15
Then
∠ A = 5y + 3 = 5(15) + 3 = 75 + 3 = 78°
∠ B = 4y + 8 = 4(15) + 8 = 60 + 8 = 68°
∠ C = 180° - (78 + 68)° ← sum of angles in triangle = 180°
∠ C = 180° - 146° = 34°
