Given $z=f(x,y),x=x(u,v),y=y(u,v),$ with $x(3,-1)=2$ and $y(3,-1)=1,$ calculate $z_s(3,-1)$ in terms of some of the values given in the table below.

$f_x(3,-1)=r{f}_y(3,-1)=b{x}_u(3,-1)=q{y}_v(3,-1)=c$

$f_x(2,1)=d,f_y(2,1)=a{x}_v(3,-1)=p{y}_v(3,-1)=2$

$z_u(3,-1)=$

$$