Restatable numbering

Question

\documentclass[11pt, oneside]{article}
\pagestyle{plain}

\usepackage{amsfonts,amssymb,amsmath,amsthm,amstext}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{proposition}[theorem]{Proposition}
\usepackage{thmtools}
\usepackage{thm-restate}

\begin{document}
  \section{Equations}
  \begin{restatable}{theorem}{xyz}
    $a = b = c.$
  \end{restatable}

  \begin{restatable}{proposition}{ab}
    Let $a = b.$ Then $b = a.$
  \end{restatable}

  \section{The same equations}

  New theorem.
  \begin{theorem}
    $a \neq d.$
  \end{theorem}
  Old theorems. 

  \xyz*
  \ab* 
\end{document}

I am using a restatable environment to repeat theorems. This works fine for {theorem}, but not for {proposition}. I would like to have the same numbering when restating a proposition (just like it happens for theorem).

Any help would be greatly appreciated, thank you.

Answer 1

First load packages, then do the settings.

\documentclass[11pt, oneside]{article}

\usepackage{amsmath,amssymb,amsthm}
\usepackage{thmtools}
\usepackage{thm-restate}

\newtheorem{theorem}{Theorem}[section]
\newtheorem{proposition}[theorem]{Proposition}

\pagestyle{plain}

\begin{document}

\section{Equations}
\begin{restatable}{theorem}{xyz}
  $a = b = c.$
\end{restatable}

\begin{restatable}{proposition}{ab}
  Let $a = b.$ Then $b = a.$
\end{restatable}

\section{The same equations}

New theorem.

\begin{theorem}
  $a \neq d.$
\end{theorem}

Old theorems. 

\xyz*

\ab* 

\end{document}

By the way, amstext is loaded automatically by amsmath and amsfonts by amssymb. I left \pagestyle{plain} even if it's redundant in order to show how to do declarations and setting.