The volume of the prism depends on the shape of its base. Since you haven't mentioned whether the base is a triangle or a rectangle, I'll solve it both ways.
1- If the base is a rectangle: volume = length x width x height = 15 x 10 x 40 = 6000 cm^3
2- If the base is a triangle: volume = area of base x height = (0.5 x 15 x 40) x 10 = 3000 cm^3
