%% 
%%  Ein Beispiel der DANTE-Edition
%%  Mathematiksatz mit LaTeX
%%  3. Auflage
%%  Beispiel 06-11-7 auf Seite 115.
%%  Copyright (C) 2018 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% ==== 
% Show page(s) 1
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\documentclass[10pt]{screxa}
\pagestyle{empty}
\setlength\textwidth{170.40707pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\setcounter{equation}{57}
\renewcommand\theequation{6.\arabic{equation}}
%StartShownPreambleCommands
\usepackage{amsmath}
%StopShownPreambleCommands
\begin{document}
\begin{subequations}
\begin{align}
y &= d\\
y &= cx+d\\
y &= bx^{2}+cx+d\\
y &= ax^{3}+bx^{2}+cx+d
\end{align}
\end{subequations}
\end{document}