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 is correct - it's The Distributive Law.
There's only 1 way - the "other way" was made up by people who don't remember The Distributive Law and/or Terms (more likely both), and very much goes against the standards.
...zero.