Hi Aveona D.
Slope Intercept Form is
y = mx + b
m = -1/2
y = (-1/2)x + b
Now use the coordinates of the point (-4, -7) to calculate b
-7 = (-1/2)(-4) + b
-7 = 2 + b
-7 - 2 = b
-9 = b
Finally plugging int the values
y = (-1/2)x - 9
You can graph your line at Desmos.com to confim that it passes through (-4, -7)