$\begin{array}{l}\phantom{\phantom{;}3x\phantom{;}+5;}{\phantom{;}x^{2}+5x\phantom{;}-4\phantom{;}\phantom{;}}\\\phantom{;}3x\phantom{;}+5\overline{\smash{)}\phantom{;}3x^{3}+20x^{2}+13x\phantom{;}-28\phantom{;}\phantom{;}}\\\phantom{\phantom{;}3x\phantom{;}+5;}\underline{-3x^{3}-5x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-3x^{3}-5x^{2};}\phantom{;}15x^{2}+13x\phantom{;}-28\phantom{;}\phantom{;}\\\phantom{\phantom{;}3x\phantom{;}+5-;x^n;}\underline{-15x^{2}-25x\phantom{;}\phantom{-;x^n}}\\\phantom{;-15x^{2}-25x\phantom{;}-;x^n;}-12x\phantom{;}-28\phantom{;}\phantom{;}\\\phantom{\phantom{;}3x\phantom{;}+5-;x^n-;x^n;}\underline{\phantom{;}12x\phantom{;}+20\phantom{;}\phantom{;}}\\\phantom{;;\phantom{;}12x\phantom{;}+20\phantom{;}\phantom{;}-;x^n-;x^n;}-8\phantom{;}\phantom{;}\\\end{array}$

$x^{2}+5x-4+\frac{-8}{3x+5}$