36-у^2/у-8*(у/у-6 — 2 у/у^2-12 у +36)+12 у/у-6

(6-y) (6+y) / (y-8) (y/ (y-6) -2y/ (y-6) ^2)+12y/ (y-6)=(6-y) (6+y) / (y+8)*(y^2-8y) / (y-6) ^2+(12-y) / (y-6)=-y (6+y) / (y-6)+12y/ (y-6)=(-6y-y^2+12y) / (y-6)=(6y-y^2) / (y-6)=y (6-y) / (y-6)=-y