Question

How can I solve the question:
If F(x,y,u,v,w)=0, G(x,y,u,v,w)=0, and H(x,y,u,v,w)=0 find
a.) (∂u/∂x) y is constant
b.) (∂w/∂u) x is constant
c.) (∂y/∂u) w is constant