Question

@agent0smith

Answer 1

find the volume

Answer 2

five hundred eighty-eight cubic inches

seven hundred eighty-four cubic inches

nine hundred fifteen cubic inches

nine hundred eighty cubic inches

Answer 3

The volume is 2.5 time that of one of the two cubes

Answer 4

huh?

Answer 5

You see that the two "cubes" are identical, with sides 7, 7 and 8 units.
The triangular prism turns out to be half of a "cube" with the same dimensions.
So calculate the volume of one of the two cubes, and multiply by 2.5 should give you the correct answer.