Angle FAE = Angle FAC = (1/2) (arc AB + arc BC) .....so.....
65 = (1/2) ( 60 + arc BC) multiply through by 2
130 = 60 + arc BC
Arc BC = 130 - 60 = 70°
So angle BAC =(1/2) ( arc BC) = (1/2)( 70) = 35° = angle GAC
Likewise angle GCA = (1/2) ( arc BC + AB) = (1/2) ( 70 + 60) = (1/2)( 130) = 65°
Therefore angle AGC = 180 - angle GAC - angle GCA = 180 - 35 -65 = 80°