$\begin{array}{l}\phantom{-x\phantom{;}+3;}{-4x^{2}-12x\phantom{;}-36\phantom{;}\phantom{;}}\\-x\phantom{;}+3\overline{\smash{)}\phantom{;}4x^{3}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-x\phantom{;}+3;}\underline{-4x^{3}+12x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-4x^{3}+12x^{2};}\phantom{;}12x^{2}\phantom{-;x^n}\phantom{-;x^n}\\\phantom{-x\phantom{;}+3-;x^n;}\underline{-12x^{2}+36x\phantom{;}\phantom{-;x^n}}\\\phantom{;-12x^{2}+36x\phantom{;}-;x^n;}\phantom{;}36x\phantom{;}\phantom{-;x^n}\\\phantom{-x\phantom{;}+3-;x^n-;x^n;}\underline{-36x\phantom{;}+108\phantom{;}\phantom{;}}\\\phantom{;;-36x\phantom{;}+108\phantom{;}\phantom{;}-;x^n-;x^n;}\phantom{;}108\phantom{;}\phantom{;}\\\end{array}$

$-4x^{2}-12x-36+\frac{108}{3-x}$