Answer:
b
Step-by-step explanation:
∠ BDC + ∠ ADC = ∠ ADB , substitute values
- 6x + 53 - 9x + 22 = 90
- 15x + 75 = 90 ( subtract 75 from both sides )
- 15x = 15 ( divide both sides by - 15 )
x = - 1
Then
∠ ADC = - 9x + 22 = - 9(- 1) + 22 = 9 + 22 = 31° → b
