To create a two-column layout with a ratio of 7:3 in LaTeX, you can use the `multicol` package [2][3][5]. Here's an example code snippet that creates a two-column layout with a ratio of 7:3:

\documentclass{article}
\usepackage{multicol}
\usepackage{lipsum} % for dummy text

\begin{document}

\begin{multicols}{2}[\columnsep=2cm]
\lipsum[1-10]
\end{multicols}

\end{document}

In this example, the `multicols` environment is used to create a two-column layout. The optional argument `[2]` specifies the number of columns, and the optional argument `[\columnsep=2cm]` sets the distance between the columns to 2cm. The `lipsum` package is used to generate dummy text for demonstration purposes.

You can adjust the ratio of the columns by changing the width of the `multicols` environment and adjusting the column separation accordingly. For example, to create a two-column layout with a ratio of 3:7, you can use the following code:

\begin{multicols}{2}[\columnsep=4cm]
\lipsum[1-10]
\end{multicols}

In this example, the `multicols` environment is twice as wide as the previous example, and the column separation is set to 4cm to achieve a ratio of 3:7.