#### Answer

$y+7=0$

#### 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 $
\left(
2,-7
\right)$ and with a slope of $m=
0
$ (since the line is horizontal), is
\begin{array}{l}\require{cancel}
y-(-7)=0(x-2)
\\\\
y+7=0(x-2)
\\\\
y+7=0
.\end{array}