$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}+1;}{\phantom{;}10x^{2}-15x\phantom{;}+18\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}+1\overline{\smash{)}\phantom{;}10x^{3}-5x^{2}+3x\phantom{;}-5\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}+1;}\underline{-10x^{3}-10x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-10x^{3}-10x^{2};}-15x^{2}+3x\phantom{;}-5\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+1-;x^n;}\underline{\phantom{;}15x^{2}+15x\phantom{;}\phantom{-;x^n}}\\\phantom{;\phantom{;}15x^{2}+15x\phantom{;}-;x^n;}\phantom{;}18x\phantom{;}-5\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+1-;x^n-;x^n;}\underline{-18x\phantom{;}-18\phantom{;}\phantom{;}}\\\phantom{;;-18x\phantom{;}-18\phantom{;}\phantom{;}-;x^n-;x^n;}-23\phantom{;}\phantom{;}\\\end{array}$

$10x^{2}-15x+18+\frac{-23}{x+1}$