# Gather vs aligned - centered equation with one number

What is the way to achieve something between gather and aligned?

\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage[utf8]{inputenc}

\begin{document}
\begin{gather}
3(a-x) = 3.5x + a - 1 \\
3a - 3x = 3.5x + a -1 \\
a = \frac{13}{4}x - \frac{1}{2}
\end{gather}

\begin{equation}
\begin{aligned}
3(a-x) = 3.5x + a - 1           \\
3a - 3x = 3.5x + a -1           \\
a = \frac{13}{4}x - \frac{1}{2}
\end{aligned}
\end{equation}
\end{document}


Result: But... How to achieve something like this? I'd like to keep the centering. Is this possible somehow?

The gathered environment, used within math mode, is what you're looking for.

\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage[utf8]{inputenc}
\begin{document}
\begin{equation}
\begin{gathered}
3(a-x) = 3.5x + a - 1 \\
3a - 3x = 3.5x + a - 1 \\
a = \frac{13}{4}x - \frac{1}{2}
\end{gathered}
\end{equation}
\end{document} Wikibooks LaTeX has a fairly nice list of the different kinds of equation and align environments.

• This works great, but the numbering is put at the bottom if the equation is too big. Is there a way to force the number to be on the center (right)? Jun 21, 2018 at 15:07
• @GuilhermeSalomé place \kern-50pt before \begin{gathered} Here I used an arbitrary/context dependent negative left shift of length 50pt. Specifically, you can use any length to suit your need. Warning: most would advise against this because the math will overlap the left margin. Feb 23, 2021 at 23:14
• You probably want to use aligned instead of gathered. Just swap the terms and add &s to the =s. Aug 8, 2022 at 16:01