Question 1074800
The drawing looks (sort of) like this:
{{{drawing(350,300,-2,33,-2,28,
green(triangle(0,8,31,8,20,14)),
green(triangle(20,26,31,8,20,14)),
green(triangle(0,8,20,26,20,14)),
triangle(0,8,11,0,11,12),triangle(31,8,11,0,11,12),
triangle(0,8,0,20,11,12),triangle(31,8,31,20,11,12),
triangle(20,26,0,20,11,12),triangle(20,26,31,20,11,12),
locate(-1,8,A),locate(31.2,8,H),locate(19.5,14,E),
locate(-1,21,B),locate(31.2,21,G),locate(19.5,27.3,F),
locate(10.5,13.6,C),locate(10.5,0,D)
)}}}

The prism has the diagonals of all its 6 faces marked.
Those diagonals split each rectangular face of the prism into two congruent right triangles,
with each of those triangles being half of a rectangular face of the prism.

Slicing along those diagonals,
they cut off 4 pyramids out of 4 corners of the prism,
to leave pyramid ACFH.
The volume of each of the pyramids cut off is {{{1/6}}} of the volume of the prism.
After removing {{{4(1/6)=2/3}}} of the volume of the prism,
they are left with {{{1-2/3=1/3}}} of the volume of the prism.
Since the volume of the prism (in cubic units) is {{{2*3*5}}} ,
the volume left (the volume of ACFH) is
{{{2*3*5/3=2*5=highlight(10)}}} .