What I find really fascinating is that the route of administration can affect your tolerance even if the potency theoretically should be the same. If you consume edibles often (eg for health reasons) you'll find you increasingly need larger and larger doses until it plateaus somewhere. If you "switch it up" and consume the same quantity via, say, a concentrate you vaporize, it'll hit you a lot harder. Even if you don't change the route of administration but the circumstances (like a new location) there's a similar effect.
So it was 40mg. I was super high on the bus on my way home, I cannot deny. Thankfully I could still handle and enjoy it. I think if it was 50mg, it would have been a whole different experience.
In my comment above, I meant to say 2 10mg doses, since we were talking about adding up to 20mg. It's the kind of mistake that's fine as a typo, but quite a different thing irl.