Answer:
∠ ABD = 108°
Step-by-step explanation:
from the diagram
∠ ABD = ∠ ABC + ∠ CBD ( substitute values )
5x - 12 = 3x + x + 12
5x - 12 = 4x + 12 ( subtract 4x from both sides )
x - 12 = 12 ( add 12 to both sides )
x = 24
Then
∠ ABD = 5x - 12 = 5(24) - 12 = 120 - 12 = 108°
