[tex]a^0=1\ \text{for any real number except 0}\\\\\text{Therefore if}\ h\neq0,\ h^0=1.\\\\\dfrac{-3g^{-2}hk^{-2}}{-6h^0}=\dfrac{-3}{-6}g^{-2}hk^{-2}=\dfrac{1}{2}\cdot\dfrac{1}{g^2}\cdot h\cdot\dfrac{1}{k^2}=\boxed{\dfrac{h}{2g^2k^2}}\\\\Used\ a^{-n}=\dfrac{1}{a^n}[/tex]