Find the slope-intercept formula:
y= mx+b
Where:
m = slope (rate of change)
b= y-intercept ( initial value)
Apply the slope formula:

where the coordinates points are from the table:
(x1,y1) = (-5,7)
(x2,y2) = (-3,1)
Replace:

So far we have:
y= -3x+b
Replace (x,y) by a coordinate point from the table (-5,7)and solve for b
7 = -3(-5) + b
7= 15+b
7-15 = b
-8 = b
Equation:
y= -3x-8
rate of change: -3
initial value = -8