latex cheat sheet index card

sample1.tex

%% Setup to use an index card
\documentclass[10pt]{book}
\usepackage[vcentering,dvips]{geometry}
\geometry{papersize={3in,5in},total={2.9in,4.9in}}

%% render a frame marking the margins of a document
% \usepackage{showframe}

%% show landscape view
\usepackage{pdflscape}

%% Use for testing by filling junk (lorem-ipsum) information
\usepackage{lipsum}

\begin{document}
\begin{landscape}

%% Use for testing by filling junk (lorem-ipsum) information
\lipsum[1]

\end{landscape}
\end{document}

sample2.tex

%% Helpful references and links
% https://tex.stackexchange.com/questions/445410/making-an-equation-sheet-for-a-3-x-5-index-card
% https://tex.stackexchange.com/questions/337/how-to-change-certain-pages-into-landscape-portrait-mode
% http://mirror.las.iastate.edu/tex-archive/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.pdf

% Set up the index card dimensions and view it in landscape mode
\documentclass[7pt]{article}
\usepackage[landscape]{geometry}
\geometry{papersize={3in,5in},total={2.9in,4.9in}}

% Use the 
\usepackage[poster]{tcolorbox}
\pagestyle{empty}

% {equation*} does not work without this package
\usepackage{amsmath}

%\usepackage{amsfonts, amssymb}
%\usepackage{physics}

\usepackage{lipsum}

\begin{document}

    \begin{tcbposter}[
        coverage = {spread},
        poster = {
            showframe,
            columns=3,
            rows=1
        }
    ]
        \posterbox[
        top=1pt,
        bottom=1pt,
        left=1pt,
        right=1pt,
        tile,
        colback=white,
        ]{
          name=Col,
          sequence = 1 between top and bottom then
                     2 between top and bottom then
                     3 between top and bottom,
        }{
            \scriptsize
            \begin{flalign*}% left aligned
                X &= \frac{\text{moles of X }}{\text{L solution}}
                \\
                \Delta \mathrm{T_F} &= -i \cdot m \cdot K_{F}
                \\
                \Delta \mathrm{T_B} &= i \cdot m \cdot K_{B}
                \\
                \Delta \mathrm{T_B} &= i \cdot m \cdot K_{B}
                \\
                &% Need tailing alignment char to get all the way left
            \end{flalign*}
        }

    \end{tcbposter}

\end{document}