Find the vertex, focus, directrix, and focal width of the parabola. -1/40 x^2=y

That is
(x-h)²=4p(y-k)
the vertex is (h,k)
and p is the distance from focus to vertex
if the parabola opens down, p is negative
if the parabola opens up, p is positive
so

(-1/40)x²=y
times both sides by -40
(x-0)²=-40(y-0)
(x-0)²=4(-10)(y-0)
p is negative so

vertex is (0,-10)
directix is y=10

to find focal width
find the x values of the function at y=-10
-1/40x²=10
times -40 both sides
x²=400
x=+/-20
x=-20 or 20
distance between 20 and -20 is 40
so focal width is 40

vertex is (0,0)
focus is (0,-10)
directix is y=10
focal width is 40