\begin{tikzpicture}
  \begin{axis}[
    xlabel = $x$, ylabel = $y$,
    width = 10cm, height=10cm,
    axis lines = middle,
    grid,
    xmin=-1.5, xmax=5.5,
    ymin=-2.5, ymax=4.5,
    legend pos=outer north east
  ]
    \addplot+ [
      no marks,
      domain = 0:4,
    ]{x-1};
    \addlegendentry{$y=x-1$}

    \addplot+ [
      no marks,
      domain = 0:4,
    ]{3-x};
    \addlegendentry{$y=3-x$}

    \node[label={90:{(2,\ 1)}},circle,fill,inner sep=2pt] at (axis cs:2,1) {};
    
  \end{axis}
\end{tikzpicture}