Show that for $\displaystyle A \in M_n(\mathbb{R})$ and $\displaystyle x,y \in \mathbb{R}^n$

$\displaystyle x \cdot Ay = y \cdot Ax$

I get

$\displaystyle y \cdot Ax = y^t Ax$ but i cannot see where to go now

I think it may involve $\displaystyle (AB)^t=B^tA^t$