Small cubes with edge lengths of 1/4 inch will be packed into the right rectangular prism shown. how many small cubes are needed to completely fill the right rectangular prism

This question is a very hard and difficult one to answer.  The main reason
is because you said "the right rectangular prism shown" and then you didn't
show it.  So all I can tell you is this:

-- The volume of each small cube is

                   (1/4) x (1/4) x (1/4) = 1/64 cubic inch .

-- The volume of the right rectangular prism that's not shown is

   (length in inches) x (width in inches) x (height in inches) cubic inches.

The number of small cubes needed to fill the invisible right rectangular prism is ...

               (volume of the missing right rectangular prism)
divided by
               (volume of each small cube) .

That's

               (volume of the alleged right rectangular prism)
divided by
               (1/64 cubic inch)
=  (64) times (volume of the rumored right rectangular prism) .