$\frac{x-y}{8}+\frac{2y}{8}$
= $\frac{x-y+2y}{8}$
= $\frac{x+y}{8}$
$\frac{x²-x}{xy}+\frac{1-4y}{xy}$
= $\frac{x²-x+1-4y}{xy}$
$\frac{5xy-4y}{2x².2y³}+\frac{3xy+4y}{2x².2y³}$
= $\frac{5xy-4y+3xy+4y}{2x².2y³}$
= $\frac{8xy}{2x².2y³}$
= $\frac{2}{xy²}$
$\frac{x+1}{a-b}+\frac{x+1}{a-b}+\frac{x+3}{a-b}$
= $\frac{x+1+x+1+x+3}{a-b}$
= $\frac{3x+5}{a-b}$