Answer
$y=12$
Work Step by Step
Using $y-y_1=m(x-x_1)$ or the Point-Slope Form of linear equations, the equation of the line passing through $(
-3,12
)$ and with slope, $m=
0
,$ is
\begin{array}{l}\require{cancel}
y-12=0(x-(-3))
\\\\
y-12=0(x+3)
\\\\
y-12=0
\\\\
y=12
.\end{array}