Area of a prism would 1/2xBxHxL
If prism B is twice twice the Height, then compared to A the area of B would be..
1/2xBx(2H)xL.. so prism B would have twice the volume of A.
Hope this helps
Pyramids and cones have volumes which are one third of their matching cuboids and cylinders.
The volume of this pyramid = (7 x 9 x 10)/3 = 630 / 3 = 210 cu ft