LaTeX Forum

\documentclass[12pt,a4paper,ngerman]{scrartcl}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{babel}

\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{blindtext}
\begin{document}
\blindtext
\begin{subequations}
\begin{equation}
 a = b
\end{equation}
\blindtext
\begin{equation}
c \neq d
\end{equation}
\end{subequations}

\bigskip
\paragraph{Oder aber:}
\blindtext
\begin{subequations}
\begin{align}
 a &= \sqrt{2}\cdot bcdefghijklmn\\
\intertext{\blindtext}
 c &= e
\end{align}
\end{subequations}
\blindtext
\end{document}

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{equation}
a+b=c
\end{equation}
...hier sollen ein paar Zeilen dazwischen...
\begin{equation}
d+e=f
\end{equation}

\end{document}

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{subequations}
\begin{align}
&a+b=c\\
&d+e=f
\end{align}
\end{subequations}

\end{document}