Compute the vector assigned to the point \(P=(-3,5)\) by the vector field:
(a) \(\mathbf{F}(x, y)=\langle x y, y-xangle\)
(b) \(\mathbf{F}(x, y)=\langle 4,8angle\)

(c) \(\mathbf{F}(x, y)=\left\langle 3^{x+y}, \log _{2}(x+y)ightangle\)