# Mixed Grouping in Subequations

I am looking to create a subequation environment with three equations. However, I want to group the 2nd and 3rd equations with a brace on the left side. I tried this (using the empheq package):

\begin{subequations}
\begin{align}
A&=B \\
\end{align}
\begin{empheq}[left=\empheqlbrace]{align}
C&=D \\
E&=F
\end{empheq}
\end{subequations}


But the alignment (as expected) between the two sets of equations doesn't come out well. Any hints?

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I'm sure the following should be of help: Aligning across aligned equation blocks; give some feedback on your findings. – Werner Jun 25 '12 at 16:21
@Werner Thanks! That tip works great. Everything lines up automatically now (I had resigned myself to a bit of whitespace voodoo to get it done the other day). – Brian Jun 26 '12 at 18:02

If you are willing to do some manual shifting:

\documentclass[a5paper]{article}
\usepackage{amsmath}
\newcommand{\leftstuff}[2][0pt]{\smash{\raisebox{#1}{\llap{#2}}}}

\begin{document}

\begin{subequations}
\begin{align}
A&=B \\
\leftstuff[-0.65em]{\Bigg\{\;}
C&=D \\
E&=F
\end{align}
\end{subequations}

\end{document}


With the optional argument you shift the brace up or down, and I've manually specified the brace size (\Bigg) and the spacing (\;).

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Thanks for the help! That works great. – Brian Jun 27 '12 at 13:26