documentclass[tikz]{standalone}

usetikzlibrary{patterns}

begin{document}

begin{tikzpicture}[domain=-90:200, x=0.025cm, y=0.15cm]

draw[->,very thick] (-100,0) -- (250,0) node[right] {$x$};
draw[->,very thick] (0,0) -- (0,45) node[above] {$y$};

foreach x in {-4,...,10} {
    draw (20*x,0) -- (20*x,-1);
}
foreach y in {0,...,45} {
    draw (0,y) -- (-1,y);
}

draw[color=blue] plot ({x},{34}) node[right] {$MR = 34$};
draw[color=red] plot ({x},{0.0018*x*x-0.2*x+10}) node[above] {$MC = 0.0018 Q^2-0.2 Q + 10$};

fill[pattern color=green, pattern=north east lines, opacity=0.9] plot[domain=-72.5840284:183.69514] ({x},{0.0018*x*x-0.2*x+10}) -- plot ({x},{34}) -- cycle node {$DB$};

end{tikzpicture}

end{document}