In this case we use intersecting secant theorem
According to this theorem, GF*GE = GH*GA
So,we plug in the values
(x-3)*(x-3+9) =(x-2)*(x-2+6)
(x-3)*(x+6) =(x-2)*(x+4)
x^2 +6x -3x -18 =x^2 +4x -2x -8
x^2 +3x -18 =x^2 +2x -8
x^2 +3x -18 -x^2 -2x +8 =0
x -10 =0
x=10
So,FG =x-3 = 10-3 =7
