# Adding right brace and equation number

I have an eqnarray that consists of 4 lines. I would like to have a right brace } that spans the last two lines with equation number, first equation with equation number and second equation with nonumber. Some brief text explaining these two parts of the equation. Something like

a=b   (1)
c=d
x=y}
}  (2)
z=t}

• could you use align for equations? Feb 18 '16 at 14:09
• yes I could use align Feb 18 '16 at 14:10
• Do all four equations have to be aligned at the equal sign? Feb 18 '16 at 14:16
• yes. They have to be aligned at the equal sign? I forgot to write. Thanks Feb 18 '16 at 14:18
• potential duplicate: Combining split and rcases Feb 18 '16 at 14:34

Here is a quick solution. It uses a manually set size of the brace. Maybe someone can provide something more robust.

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{align}
a &{} = b \\
c &{} = d \nonumber \\
\begin{split}
x &{} = y \\
z &{} = t
\end{split} \quad \bigg \rbrace \quad \text{comment text}
\end{align}

\end{document}

• Thanks for quick solution. It is useful for me. But I wonder how can provide without setting size of the brace. Feb 18 '16 at 14:35