I wrote a (very long) blog post about those viral math problems and am looking for feedback, especially from people who are not convinced that the problem is ambiguous.
It's about a 30min read so thank you in advance if you really take the time to read it, but I think it's worth it if you joined such discussions in the past, but I'm probably biased because I wrote it :)
Schools don't teach "weak juxtaposition" - they teach the actual rules of Maths! As per what's in Maths textbooks. It's adults who've forgotten the rules who make up the "weak juxtaposition" rule. See Lennes.