TikZ - Looking for some advices to build a step-by-step calculation

Draw as image? See, if the following MWE produce what you after:

documentclass[tikz, margin=1pt]{standalone}
usetikzlibrary{arrows.meta,
                positioning}

begin{document}
    begin{tikzpicture}[
    node distance = 3mm and 0mm,
                > = {Straight Barb[scale=0.5]},
every node/.style = {inner xsep=1pt}
                        ]
node (a0)                  {=};
node (aL)  [left =of a0]   {$2x+3$};
node (aR)  [right=of a0]   {$5x-4$};
%
node (b0)  [draw, minimum width=4em,
             below=of a0]   {$-3$};
%
node (c0)  [below=of b0]   {$=$};             
node (cL)  [left =of c0]   {$2x$};
node (cR)  [right=of c0]   {$5x-7$};
%
scoped[transform canvas={xshift= 1em}]
{
draw       (aL) -- (aL |- b0.north);
draw[->]   (aL |- b0.south) -- (aL |- cL.north);
}
scoped[transform canvas={xshift=-1em}]
{
draw       (aR) -- (aR |- b0.north);
draw[->]   (aR |- b0.south) -- (aR |- cR.north);
}
    end{tikzpicture}
end{document}

Note, if needed, you can insert image in equation environment.