Answer
$\frac{x+5y}{3x-y}$ and $x\ne2y$.
Work Step by Step
$\frac{x^2+3xy-10y^2}{3x^2-7xy+2y^2}=\frac{x^2+5xy-2xy-10y^2}{3x^2-xy-6xy+2y^2}=\frac{x(x+5y)-2y(x+5y)}{x(3x-y)-2y(3x-y)}=\frac{(x+5y)(x-2y)}{(3x-y)(x-2y)}=\frac{x+5y}{3x-y}$ and $x\ne2y$.
