Respuesta :

Answer:

  • A. 91°

Step-by-step explanation:

  • ∠A ≅ ∠B as vertical angles
  • ∠B + 47° + 42° = 180° (straight angle)
  • ∠B = 180° - 89° = 91°
  • ∠A = ∠B = 91°