I know how to apply the generalized chain rule for functions of this type:

z=u^2+v^2, u=x^2y and v=xy

∂z/∂u=∂z/∂u * ∂u/∂x+∂z/∂v * ∂v/∂x etc.

I came across a function of this type:

z=f(u,v), u=x^2y^2 and v=5x+1

Because of the f(u,v), I don't know how to proceed! Anyone could give me a hint on how to find partial derivatives of this function? What is it that I don't understand?

Thanks!