[tex]( \frac{x}{x {}^{2} - 9 } ) - \frac{1}{x + 3} = \frac{1}{4x - 12} [/tex]
[tex] \frac{x}{(x - 3)(x + 3)} - \frac{1}{x + 3} = \frac{1}{4(x - 3)} [/tex]
[tex] \frac{x - (x - 3) }{(x - 3)(x + 3)} = \frac{1}{4(x - 3)} [/tex]
[tex] \frac{12(x - 3)}{(x - 3)(x + 3)} = 1[/tex]
[tex] \frac{12}{x + 3} = 1[/tex]
[tex]12 = x + 3 \\ x = 9[/tex]