I would round it to 40ml. I have no idea how much 1/6th of a cup would be. Most of my cups are different sizes too so I wouldn’t know which on to trust. Also they are oddly shaped and not transparent making it a real challenge all and all.

I’m from a country where we use metric and can’t think of anything that would normally be displayed as a fraction. Sure we know what half and third are, but they’re not used officially for anything

So those two darker green symbols would represent someone shorter or taller. Totally plausible.