Respuesta :

We are given, ∠AFD =90° AND ∠AFB=31°

∠AFD=∠AFB+∠BFC+∠CFD

FROM FIGURE, ∠AFB=∠CFD

90°=∠AFB+∠BFC+∠AFB

90=31+∠BFC+31

90=62+∠BFC

∠BFC=90-62=28°

∠BFC=∠DFE (AS GIVEN IN FIGURE)

SO ∠BFC=28° (OPTION D)