Answer
$y=3$
Work Step by Step
RECALL:
(i) Horizontal lines have equations of the form $y=k$ where $k$ is a constant.
(ii) The horizontal line $y=k$ contains the points $(x,k)$. where $x$ is any real number.
The given horizontal line contains the point $(2, 3)$, which means that $k=3$.
Thus, the equation of the horizontal line is $y=3$.
