[tex]\bf \begin{array}{lllll}
&x_1&y_1\\
% (a,b)
P&({{ -2}}\quad ,&{{ -7}})
\end{array}
\\\\\\
% slope = m
slope = {{ m}}= \cfrac{rise}{run} \implies 0
\\\\\\
% point-slope intercept
\stackrel{\textit{point-slope form}}{y-{{ y_1}}={{ m}}(x-{{ x_1}})}\implies y-(-7)=0[x-(-2)]
\\\\\\
y+7=0(x+2)\implies y+7=0\implies \stackrel{standard~form}{y=-7}
\\\\\\
\textit{or you can also say}\qquad 0x+y=-7[/tex]