\( \definecolor{colordef}{RGB}{249,49,84} \definecolor{colorprop}{RGB}{18,102,241} \)
The steady state of a chain with matrix \(\mathbf{M} = \begin{pmatrix} 0.9 & 0.1 \\ 0.4 & 0.6 \end{pmatrix}\) satisfies \(x = 4y\). Given \(x+y=1\), what is \(\pi\)?