\documentclass{book} 
\usepackage{amsmath,amssymb,amsfonts} 
\usepackage[fontsize=12pt]{fontsize} 
\pagestyle{empty} 

\begin{document} 

% Equation/Formula 1
\begin{equation}
x
\end{equation}

% Equation/Formula 2
\begin{equation}
y
\end{equation}

 \end{document}