\documentclass[tikz]{mwart} 

\usepackage[utf8]{inputenc}
\usepackage{polski}

\usepackage{tikz}
\usetikzlibrary{external}
\tikzexternalize[prefix=img/]

\tikzset{every node/.style = {font=\small}}

\begin{document}

\tikzsetnextfilename{01}
\begin{tikzpicture}

\draw[help lines] (-3.5,-3.5) grid (3.25,3.5);
\draw[line width=.75pt,->] (-3.5,0) -- (3.5,0);
\draw[line width=.75pt,->] (0,-3.5) -- (0,3.5);

\node[below] at (3.5,0) {$x$};
\node[left] at (0,3.5) {$y$};

\draw[line width=.75pt] (1,.1) -- (1,-.1) node[below] {$1$};

\draw[line width=1pt,color=teal] (-3,-3) -- (3,2) node[right] {$y=\frac{5}{6}x -\frac{1}{2}$}; 

\end{tikzpicture}

\end{document}

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