Well, all you know is that the droppers that person owns has 15 drops = 1 mL. I would suggest a little test that costs nothing except time (and a graduated cylinder if you don't have one): get a cup full of water and a graduated cylinder. Count out the drops it takes to get 5mL as measured by the graduated cylinder. Do this 5 times. Add the number of drops from each together and divide by 25 and you'll have a good average of # drops/mL for that dropper.
Let's see what I've got in the magic trash can for Mateo!
Definitely worth checking out the volume of your 36 drops, but it probably will be somewhere around 2 ml. It would be good to find a graduated cylinder that can measure to the closest 0.1ml...or at least .25 ml...if only to keep you from having to count out 72 drops for every print!
I have medical syringes (w/o the needles!) that measure to 0.1 ml -- up to 3ml. Something like that would be nice to use to draw out the solutions...pouring out small volumes is not easy and asking for accidental spills. Not a big deal with Sol #1 or #2, but costly with platinum or palladium! I use the syringes to shoot the mix under the edge of my puddle pusher.
At least with LF landscape, a bad day of photography can be a good day of exercise.