Answer:
∠ DAB = 48°
Explanation:
The sum of the 3 angles in Δ ACD = 180° , then
∠ CAD + 60° + 90° = 180° , that is
∠ CAD + 150° = 180° ( subtract 150° from both sides )
∠ CAD = 30°
Then
∠ DAB + ∠ CAD = ∠ CAB
∠ DAB + 30° = 78° ( subtract 30° from both sides )
∠ DAB = 48°