The matrix
\[\begin{pmatrix} -\frac{7}{25} & \frac{24}{25} \\ \frac{24}{25} & \frac{7}{25} \end{pmatrix}\]corresponds to reflecting over a certain vector $\begin{pmatrix} x \\ y \end{pmatrix}.$  Find $\frac{y}{x}.$
Note that the reflecting $\begin{pmatrix} x \\ y \end{pmatrix}$ over itself results in itself, so
\[\begin{pmatrix} -\frac{7}{25} & \frac{24}{25} \\ \frac{24}{25} & \frac{7}{25} \end{pmatrix} \begin{pmatrix} x \\ y \end{pmatrix} = \begin{pmatrix} x \\ y \end{pmatrix}.\]Then $-\frac{7}{25} x + \frac{24}{25} y = x$ and $\frac{24}{25} x + \frac{7}{25} y = y.$  Both equations lead to $\frac{y}{x} = \boxed{\frac{4}{3}}.$