IV Flow rate calculation...Please Help

Here is the question:

order: cimetidine 300 mg IV push stat

supply: cimetidine 300 mg per 2 mL

package insert instruction: For direct IV injection, dilute 300 mg in 0.9% NaCl to a total volume of 20 mL. Inject over at least 2 minutes.

Prepare ____ mL cimetidine.

Dilute with ____ mL 0.9 % NaCl for a total of 20 mL of solution.

Administer ____ mL/min or ____ mL per 15 sec.

I am having trouble with the second and third part of this question. I already got "prepare 2mL of cimetidine."

However, I don't understand how the book got 18mL for the dilute and 10 mL/min or 2.5 mL per 15 sec.

Do you get 18 mL because if you do 20 mL of total volume - 2 mL prepared of cimetidine?

Just need help setting up the problem the find mL/min

PLEASE HELP ME.