Answer
$$y=-\frac{2}{3}x+\frac{13}{3} .$$
Work Step by Step
First, we find the slope as follows $$ m=\frac{y_2-y_1}{x_2-x_1}=\frac{1-3}{5-2}=-\frac{2}{3} .$$ In terms of the slope and a point, the standard equation of a line is $$y-y_1=m(x-x_1)$$ that is, the equation for the given line is $$y-3=-\frac{2}{3}(x-2)\Longrightarrow y=-\frac{2}{3}x+\frac{4}{3}+3=-\frac{2}{3}x+\frac{13}{3} .$$
