$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}-3;}{\phantom{;}12x^{2}+36x\phantom{;}+108\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}-3\overline{\smash{)}\phantom{;}12x^{3}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{\phantom{;}x\phantom{;}-3;}\underline{-12x^{3}+36x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-12x^{3}+36x^{2};}\phantom{;}36x^{2}\phantom{-;x^n}\phantom{-;x^n}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n;}\underline{-36x^{2}+108x\phantom{;}\phantom{-;x^n}}\\\phantom{;-36x^{2}+108x\phantom{;}-;x^n;}\phantom{;}108x\phantom{;}\phantom{-;x^n}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n-;x^n;}\underline{-108x\phantom{;}+324\phantom{;}\phantom{;}}\\\phantom{;;-108x\phantom{;}+324\phantom{;}\phantom{;}-;x^n-;x^n;}\phantom{;}324\phantom{;}\phantom{;}\\\end{array}$

$12x^{2}+36x+108+\frac{324}{x-3}$