\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}[
varint/.style={
% The shape:
rectangle,
% The size:
minimum size=10mm,
% The border:
very thick,
draw=red!50!black!50,
% The filling:
top color=white,
bottom color=red!50!black!20, % and something else at the bottom
% Font
font=\itshape
}]
\node (T1) [varint] {?};
\node (T2) [varint,right=of T1] {?};
\node (T3) [varint,right=of T2] {?};
\node (T4) [varint,right=of T3] {?};
\node (tomadas) [varint,right=of T4] {?};
\node (notebooks) [varint,right=of tomadas] {?};
\node [above] at (T1.north) {\texttt{T1}};
\node [above] at (T2.north) {\texttt{T2}};
\node [above] at (T3.north) {\texttt{T3}};
\node [above] at (T4.north) {\texttt{T4}};
\node [above] at (tomadas.north) {\texttt{tomadas}};
\node [above] at (notebooks.north) {\texttt{notebooks}};
\end{tikzpicture}
\begin{verbatim}
scanf("%i %i %i %i", &T1, &T2, &T3, &T4);
\end{verbatim}
$$
\Longleftarrow \mathtt{2~4~3~2}
$$
\begin{tikzpicture}[
varint/.style={
% The shape:
rectangle,
% The size:
minimum size=10mm,
% The border:
very thick,
draw=red!50!black!50,
% The filling:
top color=white,
bottom color=red!50!black!20, % and something else at the bottom
% Font
font=\itshape
}]
\node (T1) [varint] {2};
\node (T2) [varint,right=of T1] {4};
\node (T3) [varint,right=of T2] {3};
\node (T4) [varint,right=of T3] {2};
\node (tomadas) [varint,right=of T4] {?};
\node (notebooks) [varint,right=of tomadas] {?};
\node [above] at (T1.north) {\texttt{T1}};
\node [above] at (T2.north) {\texttt{T2}};
\node [above] at (T3.north) {\texttt{T3}};
\node [above] at (T4.north) {\texttt{T4}};
\node [above] at (tomadas.north) {\texttt{tomadas}};
\node [above] at (notebooks.north) {\texttt{notebooks}};
\end{tikzpicture}
\begin{verbatim}
tomadas = T1 + T2 + T3 + T4;
\end{verbatim}
\begin{tikzpicture}[
varint/.style={
% The shape:
rectangle,
% The size:
minimum size=10mm,
% The border:
very thick,
draw=red!50!black!50,
% The filling:
top color=white,
bottom color=red!50!black!20, % and something else at the bottom
% Font
font=\itshape
}]
\node (T1) [varint] {2};
\node (T2) [varint,right=of T1] {4};
\node (T3) [varint,right=of T2] {3};
\node (T4) [varint,right=of T3] {2};
\node (tomadas) [varint,right=of T4] {11};
\node (notebooks) [varint,right=of tomadas] {?};
\node [above] at (T1.north) {\texttt{T1}};
\node [above] at (T2.north) {\texttt{T2}};
\node [above] at (T3.north) {\texttt{T3}};
\node [above] at (T4.north) {\texttt{T4}};
\node [above] at (tomadas.north) {\texttt{tomadas}};
\node [above] at (notebooks.north) {\texttt{notebooks}};
\end{tikzpicture}
\begin{verbatim}
notebooks = tomadas - 3;
\end{verbatim}
\begin{tikzpicture}[
varint/.style={
% The shape:
rectangle,
% The size:
minimum size=10mm,
% The border:
very thick,
draw=red!50!black!50,
% The filling:
top color=white,
bottom color=red!50!black!20, % and something else at the bottom
% Font
font=\itshape
}]
\node (T1) [varint] {2};
\node (T2) [varint,right=of T1] {4};
\node (T3) [varint,right=of T2] {3};
\node (T4) [varint,right=of T3] {2};
\node (tomadas) [varint,right=of T4] {11};
\node (notebooks) [varint,right=of tomadas] {8};
\node [above] at (T1.north) {\texttt{T1}};
\node [above] at (T2.north) {\texttt{T2}};
\node [above] at (T3.north) {\texttt{T3}};
\node [above] at (T4.north) {\texttt{T4}};
\node [above] at (tomadas.north) {\texttt{tomadas}};
\node [above] at (notebooks.north) {\texttt{notebooks}};
\end{tikzpicture}
\begin{verbatim}
printf("%i\n", notebooks);
\end{verbatim}
$$
\Longrightarrow \mathtt{8}
$$
\end{document}