The bisected angle sets up the following relationship :
(6x)/ (7x) = (9x) /( 11x - 4) cross-multiply
6x ( 11x - 4) = 9x * 7x
66x^2 - 24x = 63x^2
66x^2 - 63x^2 = 24x
3x^2 - 24x = 0
3x ( x - 8) = 0
The second factor set to 0 is what we need
x - 8 = 0
x = 8
