$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}-3;}{\phantom{;}3x^{3}+9x^{2}+25x\phantom{;}+70\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}-3\overline{\smash{)}\phantom{;}3x^{4}\phantom{-;x^n}-2x^{2}-5x\phantom{;}+3\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}-3;}\underline{-3x^{4}+9x^{3}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-3x^{4}+9x^{3};}\phantom{;}9x^{3}-2x^{2}-5x\phantom{;}+3\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n;}\underline{-9x^{3}+27x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{;-9x^{3}+27x^{2}-;x^n;}\phantom{;}25x^{2}-5x\phantom{;}+3\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n-;x^n;}\underline{-25x^{2}+75x\phantom{;}\phantom{-;x^n}}\\\phantom{;;-25x^{2}+75x\phantom{;}-;x^n-;x^n;}\phantom{;}70x\phantom{;}+3\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n-;x^n-;x^n;}\underline{-70x\phantom{;}+210\phantom{;}\phantom{;}}\\\phantom{;;;-70x\phantom{;}+210\phantom{;}\phantom{;}-;x^n-;x^n-;x^n;}\phantom{;}213\phantom{;}\phantom{;}\\\end{array}$

$3x^{3}+9x^{2}+25x+70+\frac{213}{x-3}$