So we want to know the volume of a pyramid and of a cylinder. The volume of a pyramid is given by the formula: V=(a*b*h)/3 where a=10 m and b=10 m are the sides and h=9 m is the height of the pyramid. V=(10*10*9)/3=900/3=300 m^3. Volume of a cylinder is V=r^2*π*h where r is the radius and its one half of the diameter d=20 km, and h=12 km is the height. So V=10^2*3.14*12=3769.91 km^3.