Composition of two invertible linear maps

Question

Prove or disprove:

Let $A,B: {\Bbb R}^n \rightarrow {\Bbb R}^n$ be linear. If $A,B$ are both invertible, then $A\circ B$ is invertible

Can someone explain if this is true or false? I'm trying to come up with examples but I don't know where to start.