Don't use air dusters. Terrible reactions with my chemicals for some reason, the concentrate absorbed most of the air. Rather weird. Stick with Nitrogen or Butane or other known inert gasses.
Developer Bottles A and C have 500 mL and B has 222 mL. If you mix 50-22.2-50 starting with 800 mL of water and adding up to one liter than you should be good. Stir for a minute between the addition of each concentrate. I usually mix up a gallon at a time.