Figures.tex

\usepackage{graphicx}
\usepackage{caption}

\captionsetup[figure]{labelfont={bf},name={Fig.},labelsep=period}

\begin{figure}[h!]
    \centering
    \includegraphics[width=12.5cm]{figs/fig77.png}
    \caption{asd}
    \label{fig:7.7}
\end{figure}

Generals.tex

% Decimal point as separator
\usepackage[spanish]{babel}
\decimalpoint

% to switch off page numbering.
\pagenumbering{gobble}

% enumerate with alphabetical items
\begin{enumerate}[label=(\alph*)]
    \item
    \item
\end{enumerate}

% bullet in itemize
\begin{itemize}
    \renewcommand{\labelitemi}{$\bullet$}
    \item 
    \item 
\end{itemize}

% Degrre symbol
% with pacjage
% http://ctan.math.washington.edu/tex-archive/macros/latex/contrib/was/gensymb.pdf
\usepackage{gensymb}
\degree
\celsius
% or without
$^{\circ}$

% SI unites
% http://ctan.math.washington.edu/tex-archive/macros/latex/contrib/siunitx/siunitx.pdf
\usepackage{siunitx}

\num{123}      % 123
\num{3.45d-4}   % 3.45×10^−4
\num{-e10}      % −10^10

\SI[options]{number}[preunit]{unit}
\SI[mode=text]{1.23}{J.mol^{-1}.K^{-1}}
\SI{.23e7}{\candela}
\SI[per-mode=symbol]{1.99}[\$]{\per\kilogram}
\SI[per-mode=fraction]{1,345}{\coulomb\per\mole}



$$
\begin{matrix}
a & b \\
c & d
\end{matrix}
\quad
\begin{pmatrix}
a & b \\
c & d
\end{pmatrix}
\quad
\begin{bmatrix}
a & b \\
c & d
\end{bmatrix}
\quad
\begin{vmatrix}
a & b \\
c & d
\end{vmatrix}
\quad
\begin{Vmatrix}
a & b \\
c & d
\end{Vmatrix}
$$