Suppose $L$ is a function such that $L'(x)=1/x$ for $x>0$. Find an expression for the derivative of each function below:
(a) $f(x)=L(x^{3})$
(b) $g(x)=L(7 x)$
(c) $h(x)=L(1/x)$

(a) $f'(x)=$
(b) $g'(x)=$
(c) $h'(x)=$