\documentclass[12pt]{article}
\usepackage{amssymb,amsmath,amscd,concmath,amsfonts}
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\begin{document}
\begin{equation*}
\begin{aligned}
  \dot x &= f(x, u) &\quad x &\in R^n, u \in R \\
  y &= h(x, u) & y &\in R
\end{aligned}
\end{equation*}
\end{document}