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 :)
It's not taught 2 different ways. It's taught the same around the world (the mnemonics are different but the rules are the same), there's just 2 types of people - those who remember the rules and those who don't. You'll notice students never get these questions wrong, only adults who've forgotten the rules.