Here are a few rules that apply to this expression:
Firstly, solve the exponent: [tex] (-6x)^{-2}=-6^{-2}x^{1*-2}=-6^{-2}x^{-2} [/tex]
Next, convert the negative exponents: [tex] -6^{-2}x^{-2}=-\frac{1}{6^2x^2}=-\frac{1}{36x^2} [/tex]
Your final answer is -1/36x^2.