Clinical calculation question

The sample clinical calculation test question reads:
"How much diluent will be needed tho five (fix?) a solution of 25,000 units per cc if the vial contains 20,000 units of dry drug?

I say 0.8 cc, but the answer key says 8.0 cc's

Show me the calculation, please. This is a sample question for a Federal LPN Job with the VA System, so it's VERY IMPORTANT!!!!!