A table of values for $f,g,f',$ and $g'$ is given below:

(a) If $F(x)=f(f(x))$, find $F'(2)$.
(b) If $G(x)=g(g(x))$, find $G'(3)$.

(a) $F'(2) =$
(b) $G'(3) =$