Please help and leave explanation

Answer: x = 150°
Step-by-step explanation:
The tangent intersects the circle's radius at a 90° angle, so ∠OAC = ∠OBC = 90°.
AOBC is a quadrilateral and we know that sum of interior angles of quadrilateral equals to 360°.
Now,
∠OAC + ∠OBC + ∠AOB + ∠ACB = 360°
90° + 90° + x + 30° = 360°
210° + x = 360°
x = 360° - 210°
x = 150°