Consider quadrilateral DECF. As for any quadrilateral, the sum of its interior angles is 360°. The angles D and C of this quadrilaterals are right angles; their sum is 90° + 90° = 180°. Hence, the sum of angles F and E of this quadrilateral is 360° - 180° = 180°. Thus the angle CFD is the supplementary angle to angle E: ∠CFD = 180° - 57° = 123°. But the angle BFD is the supplementary angle to the angle CFD. So, we conclude that ∠BFD = 180° - 123° = 57°. ANSWER. ∠BFD = 57°.