equations

lv.tex

\documentclass[12pt]{article}
\usepackage[paperwidth=7in,paperheight=5in]{geometry}
\usepackage{amsmath}
\usepackage{graphicx}

\usepackage[T1]{fontenc}
\usepackage{fourier}

\begin{document}\Huge
\thispagestyle{empty}
\topskip0pt

\vspace*{\fill}
$$
\resizebox{12cm}{!}{
\begin{cases}
    x' =  & x \times \left(\alpha - \beta y\right) \\
    y' =  & y \times \left(\gamma x - \delta\right)
\end{cases}
}
$$
\vspace*{\fill}

\end{document}

mte.tex

\documentclass[12pt]{article}
\usepackage[paperwidth=7in,paperheight=5in]{geometry}
\usepackage{amsmath}
\usepackage{graphicx}

\usepackage[T1]{fontenc}
\usepackage{fourier}
\usepackage{xfrac}

\begin{document}\Huge
\thispagestyle{empty}
\topskip0pt

\vspace*{\fill}

\resizebox{12cm}{!}{
    $\frac{B}{M} = b_0M^{-\sfrac{1}{4}}e^{-\sfrac{E}{kT}}$
}

\vspace*{\fill}

\end{document}