For the sake of ease, I will split this prism into 2 prisms. One prism will be 2x4x5 while the second one will be 4x5x6. The volume of the prism will be the sum of the volume of both prisms.
Prism A: Volume would be lwh or 2*4*5=40
Prism B: Volume would also be lwh which is 4*5*6=120
