Work Step by Step
RECALL: A horizontal line has a slope of zero and has an equation of the form $y=k$ where $k$ the coordinate of all the points on the line. The line has a slope of zero therefore the line must be horizontal. The horizontal line passes through the point $(1, 3)$. The y-coordinate of the point $(1, 3)$ is $3$. Thus, equation of the line is $y=3$.