Chemistry
posted by Brittany .
You wish to prepare 0.18 M HNO3 from a stock solution of nitric acid that is 18.9 M. How many milliliters of the stock solution do you require to make up 1.00 L of 0.18 M HNO3?

M x mL = M x mL.
18.9 M x mL = 0.18 M x 1000 mL 
I don't understand what to do.

solve for ml
(it's a dilution equation)
You have the initial concentration and final concentration with volume of it that you want. All you need is the initial volume of concentrated nitric acid you want to remove from the concentrated stock volume, to use to dilute to the needed concentration.