Hi there!

We know that the equation for the volume of a pyramid is:
V = 1/3(bh)
We know that:
V = 200 km³
b = 12 × 5 = 60 km²
We can plug these into the equation:
200 = 1/3(60)(h)
Simplify:
200 = 20h
Divide both sides by 20:
200/20 = 20h/20
h = 10 km
The equation is put in slope intercept form which is y=mx+b
The slope is m and in this case it is -1/2.
To find the y intercept substitute in 0
for x then solve.

Ax + z = aw - y....subtract aw from both sides
ax - aw + z = -y....subtract z from both sides
ax - aw = -y - z....factor out a on the left side
a(x - w) = -y - z...divide both sides by (x-w)
a = (-y - z) / (x - w)
The slope of the inverse is 1/2.