Respuesta :

y= mx+b
5= -7x + b
7x + 5 =b

idk where to go from there, but hope this helps somewhat!
As the line is Horizontal, y-coordinate would be same for all instances, hence slope would be: 0

m = y2 - y1 / x2-x1
m = 0 / x2-x1
m = 0

Now, y-y1 = m(x-x1)
y - 5 = 0(x+7)
y = 5

Simply, Your Equation would be y = 5

Hope this helps!