Answer
$y=-4$.
Work Step by Step
Horizontal line passing through the point $\left( 7,-4 \right)$.
The line is horizontal; therefore, its slope is zero.
Put the provided values in the point slope form of a straight line $\left( y-{{y}_{1}} \right)=m\left( x-{{x}_{1}} \right)$.
$\begin{align}
& \left( y-{{y}_{1}} \right)=m\left( x-{{x}_{1}} \right) \\
& y-\left( -4 \right)=0\left( x-7 \right) \\
& y=-4
\end{align}$
Thus, the equation in slope-intercept form of a line is $y=-4$.
