Answer:
third angle = (-6x + 161)°
Step-by-step explanation:
180° = (x)° + (5x + 19)° + third angle →
180° = (6x + 19)° + third angle →
180° – (6x + 19)° = (6x + 19)° + third angle – (6x + 19)° →
180° – (6x + 19)° = third angle →
180° + -(6x + 19)° = third angle →
180° + (-6x)° + (-19)° = third angle
180° – 6x° – 19° = third angle
(180° – 19°) – 6x° = third angle
161° – 6x° = third angle
third angle = 161 – 6x°
third angle = -6x° + 161°
third angle = (-6x + 161)°
