$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}-3;}{\phantom{;}3x^{4}+9x^{3}+26x^{2}+68x\phantom{;}+216\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}-3\overline{\smash{)}\phantom{;}3x^{5}\phantom{-;x^n}-x^{3}-10x^{2}+12x\phantom{;}+15\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}-3;}\underline{-3x^{5}+9x^{4}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-3x^{5}+9x^{4};}\phantom{;}9x^{4}-x^{3}-10x^{2}+12x\phantom{;}+15\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n;}\underline{-9x^{4}+27x^{3}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{;-9x^{4}+27x^{3}-;x^n;}\phantom{;}26x^{3}-10x^{2}+12x\phantom{;}+15\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n-;x^n;}\underline{-26x^{3}+78x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{;;-26x^{3}+78x^{2}-;x^n-;x^n;}\phantom{;}68x^{2}+12x\phantom{;}+15\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n-;x^n-;x^n;}\underline{-68x^{2}+204x\phantom{;}\phantom{-;x^n}}\\\phantom{;;;-68x^{2}+204x\phantom{;}-;x^n-;x^n-;x^n;}\phantom{;}216x\phantom{;}+15\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n-;x^n-;x^n-;x^n;}\underline{-216x\phantom{;}+648\phantom{;}\phantom{;}}\\\phantom{;;;;-216x\phantom{;}+648\phantom{;}\phantom{;}-;x^n-;x^n-;x^n-;x^n;}\phantom{;}663\phantom{;}\phantom{;}\\\end{array}$

$3x^{4}+9x^{3}+26x^{2}+68x+216+\frac{663}{x-3}$