functions - How to approach proving $f^{-1}(Bsetminus C)=Asetminus f^{-1}(C)$?

Let $A,B,C$ be sets such that $C\subseteq B$. Let $f: A \to B$ be a function. Prove that $f^{-1} (B\setminus C)=A\setminus f^{-1} (C).$

I really need help with this proof problem. I'm not sure where to begin or what strategy to consider using.