# Subnumber equations continuing after a line of text

Similar to this question (but not enough to be a duplicate), I am trying to have a theorem where there is a line of text in-between some of the equations, and I would like the subnumbering to continue across them. I.e.

x = y + 1 (1)

It can be shown that x = 4, therefore

y = 3 (1a)

(Ignore the non-right aligned numbering)

If I try the approach in the linked question (using \begin{subequations} and tag{}) I cannot seem to have the numbering continue as above, and instead the numbering resets (example below)

\begin{subequations}\label{eq:foo}
\begin{alignat}{2}
x = y + 1  \tag{\ref{eon:foo}} \\
\text{It can be shown that x = 4, therefore} \\
y = 3
\end{alignat}
\end{subequations}


giving

x = y + 1 (1)

It can be shown that x = 4, therefore (1a)

y = 3 (1b)

How do I make the numbering continue?

• Welcome to tex.sx. Before the second equation, insert \addtocounter{equation}{-1}. – barbara beeton Aug 21 '19 at 18:17
• @barbarabeeton Could you kindly add your own answer and then I'll remove mine? Thank you. – Sebastiano Aug 21 '19 at 19:15
• @Sebastiano -- Leave your answer. I just realized that an align environment is wanted, and alignment won't be accomplished by what I suggested. (Since I don't at the moment have a tex system available, I can't experiment.) – barbara beeton Aug 21 '19 at 19:29

My welcome to the TeX.SE. This is a fast answer but it not is a good answer with a lot of sincerity because you should put a new counter for subequations and equations.

\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}
\begin{subequations}\label{eq:foo}
\begin{alignat}{2}
x = y + 1  \tag{1} \\
\intertext{It can be shown that $x = 4$, therefore} \nonumber\\
y = 3
\end{alignat}
\end{subequations}
\end{document}