A rectangular prism with a volume of   cubic units is filled with cubes with side lengths of   unit.How many   unit cubes does it take to fill the prism?

The question seems to be missing some crucial information. To find out how many unit cubes it takes to fill the prism, we need to know the volume of the rectangular prism and the side length of the cubes.

However, the general steps to solve this problem would be:

1. Find the volume of the rectangular prism. This is usually given in the problem.
2. Find the volume of a single unit cube. Since cubes have all sides of equal length, the volume is found by cubing the side length (Volume = side length^3).
3. Divide the volume of the rectangular prism by the volume of a single unit cube. This will give you the number of unit cubes needed to fill the prism.

Without the specific numbers, I can't provide a more detailed solution.