$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}+3;}{\phantom{;}2x^{2}-6x\phantom{;}+21\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}+3\overline{\smash{)}\phantom{;}2x^{3}\phantom{-;x^n}+3x\phantom{;}+10\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}+3;}\underline{-2x^{3}-6x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-2x^{3}-6x^{2};}-6x^{2}+3x\phantom{;}+10\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n;}\underline{\phantom{;}6x^{2}+18x\phantom{;}\phantom{-;x^n}}\\\phantom{;\phantom{;}6x^{2}+18x\phantom{;}-;x^n;}\phantom{;}21x\phantom{;}+10\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n-;x^n;}\underline{-21x\phantom{;}-63\phantom{;}\phantom{;}}\\\phantom{;;-21x\phantom{;}-63\phantom{;}\phantom{;}-;x^n-;x^n;}-53\phantom{;}\phantom{;}\\\end{array}$

$2x^{2}-6x+21+\frac{-53}{x+3}$