How to prove that if $A$ and $B$ are $n\times n$ matrices then $\operatorname{rank}(A) + \operatorname{rank}(B) \le \operatorname{rank}(AB) + n$

Question

Prove that if $A$ and $B$ are $n\times n$ matrices then $\operatorname{rank}(A) + \operatorname{rank}(B) \le \operatorname{rank}(AB) + n$