Answer:
- y = 15
- ∠abc = 68°
- ∠bac = 78°
- ∠acb = 34°
Step-by-step explanation:
It is helpful to realize that the exterior angle is equal to the sum of the remote interior angles:
146° = (5y+3)° +(4y+8)°
135 = 9y . . . . . . . . . . . . . . divide by °, subtract 11
15 = y . . . . . . . . . divide by 9
∠abc = (4y+8)° = (4·15 +8)° = 68°
∠bac = (5y+3)° = (5·15 +3)° = 78°
∠acb = 180° -146° = 34°
