Answer:
When a line bisects an angle, it divides the angle into two congruent angles.
Angle FGH = Angle HGI
4x - 6 = 5x - 15
x = 9
Substitute x into angles.
Angle FGH = 4(9) - 6 = 30°
Angle HGI = Angle FGH = 30°
Angle FGI = Angle FGH + Angle HGI
= 30 + 30
= 60°