General equation of line :
[tex]y=mx+c[/tex]where:
[tex]\begin{gathered} m=\text{slope} \\ c=\text{ y-intercept} \\ (x,y)=(-2,-7) \end{gathered}[/tex][tex]\begin{gathered} y=mx+c \\ y=0(x)+c \\ -7=0(-2)+c \\ c=-7 \end{gathered}[/tex]so equation of line:
[tex]\begin{gathered} y=mx+c \\ y=0(x)-7 \\ y=-7 \end{gathered}[/tex]