# Subnumbering equations while also aligning them

Using AMSMATH's gather environment I can subnumber equations, hoewever I am also losing the alignment at the "=". Is there a way to have both, alignment and subnumbering?

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{gather}
x = a +  b +c \label{eq:gat}\\
sddsdt = a + b + d \tag{\ref{eq:gat}a} \\
yfgfdg = a + b + d \tag{\ref{eq:gat}b}
\end{gather}

\end{document} • Did you try this approach with align instead of gather? There is nothing special about gather here – daleif Apr 8 at 19:50

Note it is very easy to have a subnumbering like you seem to want, and cross-referencing it

\documentclass{article}
\usepackage{mathtools}
\usepackage{cleveref}

\begin{document}

\begin{equation}
a = b
\end{equation}

\begin{subequations}
\begin{align}
x & = a + b +c\label{eq:gat}\tag{\theequation}\\
sddsdt & = a + b + d\label{eq:gat1} \\
yfgfdg & = a + b + d \label{eq:gat2}
\end{align}
\end{subequations}
We see from \eqref{eq:gat}, \eqref{eq:gat1} and \eqref{eq:gat2} that $1 = 2$.

\end{document} • I'd prefer doing \label{eq:gat} after \begin{subequations} and \tag{\ref{eq:gat}} in the first line of the alignment. Cleaner than using \theequation. – egreg Apr 8 at 22:57