Answer:
12x - 73
Step-by-step explanation:
DFE + CFD = 12x + 7
DFE + 90 = 12x + 7
DFE = 12x + 7 - 90
DFE = 12x - 83
therefore
DFE = AFB ( vertically opposite angles are equal)
AFB = 12x - 83
