Angles on a straight line sum to 180°. Right angle = 90°.

∠AOC = 90°, so ∠COB = 90° (AOB is a straight line).
∠AOE = 71°, so ∠COE = 90° − 71° = 19°.
∠BOD = ∠COE = 19° (vertically opposite).

Final Answer: 19