A molar volume of $V,$ a binary mixture of $1$ and $2$ hoving mole fraction $x_1$ and $x_2$ respectively is given $v=220x_1-120x_2-x_1{x}_2(90x_1-50x_2).$ Find the partial molar volume of species $2$ at $x_2=0\mathrm{.}3,x_1=0\mathrm{.}7$