Respuesta :
The three interior angles of any triangle add to 180 degress. Therefore,
180-(120 + 40) = the third angle.
So, 20 is the third angle
Answer: 20°
Step-by-step explanation:
1. B = 120°, C = 40° 1. Given
2. A + B + C = 180° 2. Triangle Sum Theorem
3. A + 120° + 40° = 180° 3. Substitution Property
4. A + 160° = 180° 4. Simplify (added like terms)
5. A = 20° 5. Subtraction Property of Equality