Since sides BC and DB are equal, then we deduce angle C and angle D have the same value. From the information given we know that the angle B is 147°, therefore we can use the following equation (knowing that the addition of three angles of a triangle is equal to 180°)
C + D + B = 180°
2D + 147° = 180° ( Since C=D)
2D = 180° - 147° ( Transposing 147° to the other side of the equation)
2D = 33° ( Subtracting)
D= 33°/2 ( Isolating D)
D= 16.5 ° (Dividing)
Answer: Angle D is equal to 16.5°