Find the partial derivatives of $\displaystyle F(x,y) = f( g(x) k(y), h(x) + 2k(y) ) $.

Partial derivatives are easy for me when the function is written g(x,y) = x^2 - sin(y) or something like that, but when it's written as a composition of functions, I start to get confused. Could someone please help me with this?