Answer:
∠ ADB = 19°
Step-by-step explanation:
Consecutive angles in a parallelogram are supplementary, sum to 180° , so
∠ CDA = 180° - ∠ DAB = 180° - 138° = 42°
Then
∠ ADB + ∠ CDB = 42° , that is
∠ ADB + 23° = 42° ( subtract 23° from both sides )
∠ ADB = 19°
