Help I get one answer and they give me another

Hello,

I am having trouble understanding where they come up with their answers to these to problems, as I come up with different ones if someone can explain it to me that would be great, I did the work just came up with a different answer

• The physician ordered 80 mg of Garamycin IM BID. On hand: Garamycin 40 mg/ml.
  

How many ml should you administer? __10mL (answer they give me)

2 mL (my answer) 80/40=2

2. The physician ordered 120,000 units of Penicillin IM every 6 hrs. The label states "add 19.6 ml of diluent to provide 50,000 units/ml; add 9.6 ml of diluent to provide 100,000 units/ml; add 4.6 ml of diluent to provide 200,000 units/ml; add 3.6 ml of diluent to provide 250,000 units/ml; add 1.6 ml of diluent to provide 500,000 units/ml".

How much diluent should be added? _______4.6ml____(got the same no complaints)

How many ml should be administered? ______1.5mL(answer they give me)

.6mL (my answer) 120,000/200,000=.6