Suppose that $$f(x) = 13 x - 6 x^3.$$

(A) Find the average of the $x$ values of all local maxima of $f$.
Note: If there are no local maxima, enter -1000.

Average of $x$ values =

(B) Find the average of the $x$ values of all local minima of $f$.
Note: If there are no local minima, enter -1000.

Average of $x$ values =

(C) Find the average of the $x$ values of all inflection points of $f$.
Note: If there are no inflection points, enter -1000.

Average of $x$ values =