For Q5, I translated 21 or older as 21+, but then I thought "in the US" is another condition, so my Lawgic formula was:

21+ and in-the-US --> can-purchase-alcohol

or /can-purchase-alcohol --> /21+ or /in-the-US

Is this incorrect because I'm drawing outside inferences, or why wouldn't being in the US also be a required condition to purchase alcohol? If you're not in the US but still 21+, you still might not be able to purchase alcohol, no?

I realise now that it's because the question assumes 21+ --> (legally allowed to purchase alcohol in the US), where in the US, it is part of the necessary condition of being legal, not something separable from being legally allowed.