"FG = 14 is the answer
The two angles, <FDG and <DGF, and the non-included side, DF in ∆FDG re equal to the corresponding two angles, <EDF and <DEF, and non-included side, DF in ∆EDF. Therefore, both triangles are congruent by AAS.
This implies that:
n + 9 = 4n - 6
Collect like terms
n - 4n = -9 - 6
-3n = -15
Divide both sides by -3
n = -15/-3
n = 5
✔️FG = 4n - 6
Plug in the value of n
FG = 4(5) - 6
FG = 20 - 6 = 14"