Question

??????HOWWWWWWW???????

Answer 1

You have to figure volume of the right rectangular pyramid plus the volume of the rectangular prism.
Pyramid volume equals (length * width * height) / 3. Add this to prism volume of length * width * height

((4 * 5 * 6) / 3) + (4 * 5 * 2) =
40 + 40 =
80

Answer 2

work out the triangular base pyramid then the cube beneath