An enumeration of equations with aligned equal signs

\documentclass[leqno]{report}
\usepackage{amsmath}

\begin{document}

\begin{flalign}
1 + 1 &= 2     &\\
    1 &= 2 - 1 
\end{flalign}

\end{document}

You could use \hphantom for taking the required space for alignment:

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{enumerate}
\item $1 + 1 = 2$ 
\item $\hphantom{1+1}\mathllap{1} = 2 - 1$
\end{enumerate}
\end{document}

\usepackage{array}

\newenvironment{enumalign}
  {\par\addvspace{\topsep}\setcounter{enumi}{0}
   \noindent$\begin{array}{@{}r@{\hspace{\labelsep}}r@{}>{{}}l@{}}}
  {\end{array}$\par\addvspace{\topsep}}
\newcommand{\eitem}{\stepcounter{enumi}\makebox[\labelwidth][r]{\theenumi.}&}

\begin{document}
\begin{enumalign}
\eitem 1+1&=2\\
\eitem 1&=2-1
\end{enumalign}

Remember to end the rows with \\