the general equation of a line is
[tex]y=mx+b[/tex]where m is the slope an b an initial point
we can replace m=-7 and (x,y)=(-5,7) to find b an creat the equation for this case
[tex]\begin{gathered} (7)=(-7)(-5)+b \\ 7=35+b \\ b=-28 \end{gathered}[/tex]and the equation is
[tex]y=-7x-28[/tex]