Answer:
D
Step-by-step explanation:
Supplementary angles sum to 180°, thus
∠ A + ∠ B = 180°, that is
30° + ∠ B = 180° ( subtract 30° from both sides )
∠ B = 150°
Complementary angles sum to 90°, thus
∠ A + ∠ C = 90°, that is
30° + ∠ C = 90° ( subtract 30° from both sides )
∠ C = 60°
Thus
∠ B + ∠ C = 150° + 60° = 210° → D
