Answer:
D. 28
Step-by-step explanation:
Given:
m∠AFD = 90°
m∠AFB = 31°
Required:
m∠DFE
Solution:
m<AFB = m<CFD (both angles are marked as congruent angles)
Since m<AFB = 31°, therefore,
m<CFD = 31°
m<AFB + m<CFD + m<BFC = m<AFD
Plug in the known values
31° + 31° + m<BFC = 90°
62° + m<BFC = 90°
Subtract 62° from each side
m<BFC = 90° - 62°
m<BFC = 28°
m<BFC = m<DFE = 28° (both angles are marked congruent to each other)
Therefore,
m<DFE = 28°
