The point-slope equation is given by:
y - y' = m(x - x')
where
m = slope
(x', y') is a point that lies in the line
For our question we have:
m = -1/2
(x', y') = (-8, -1)
Let's plug that in the equation:
y - y' = m(x - x')
y - (-1) = -1/2(x - (-8) )
y + 1 = -1/2(x + 8)
y + 1 = -1/2x - 4
2y + 2 = -x - 8
x + 2y + 2 + 8 = 0
x + 2y + 10 = 0
Answer: the equation of the line is x + 2y + 10 = 0