# How to include a system of equations in a subequation environment?

I am wondering how to include a system of equations in a subequations environment.

I currently have the following document as an example :

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{subequations}
\begin{alignat}{2}
\end{alignat}
\end{subequations}
\end{document}


Here is the display :

Now, what I would like to have is the first two equation groupped into a system of equations (with a brace) and only one label to this system. Something looking like this :

Any suggestions ?

Depending on your requirements for alignment, the following should work:

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{subequations}
\begin{align}
\forall l \in L, & \quad a = 1 \\
\forall l \in L, & \quad b = 2 \\
\forall l \in L, & \quad c
\end{align}
\end{subequations}

\begin{subequations}
\begin{align}
&{\left.\kern-\nulldelimiterspace
\renewcommand{\arraystretch}{1.5}
\setlength{\arraycolsep}{0pt}
\begin{array}{l}
\forall l \in L, \quad a = 1 \\
\forall l \in L, \quad b = 2
\end{array}
\right\}} \\
&\forall l \in L, \quad c
\end{align}
\end{subequations}

\end{document}