I’ll stick my chin out, and claim that nobody who knows anything about math would ever write the expression like that. Either use parentheses or a long, horizontal division bar making it obvious what groups with what. As given, it looks like some small-minded school teacher (I’m not saying all teachers are small-minded, just a few of them!) who has taught a set of rules, with little regard for actual practice outside the classroom, and then tests to exactly those rules.