Rational Functional Equations

Suppose $f(x)$ is a rational function such that
$3 f \left( \frac{1}{x} \right) + \frac{2f(x)}{x} = x^2$
for all $x \neq 0$. Find $f(-2)$.

I tried substituting different values of $x$ to get a system of equations to solve for $f(x)$, but this didn't work. How should I take this from here?