We are given the slope m=-1 and the point (0,-2)
The point-slope form of the line is:
y - k = m(x - h)
Substituting:
y - (-2) = -1(x - 0)
Operating:
y +2 = -1(x - 0)
This was the point-slope form of the line
Rewriting in slope-intercept forn:
y +2 = -x
Subtracting 2:
y = -x - 2
That is the slope-intercept form of the line