Many of the things we believe about ourselves and our experiences turn out to be false. Sometimes this is due to innocent memory failures or to the lack of needed information.

Suppose that Charles believes that he failed his biology test because the professor asked obscure and ambiguous questions.
Charles believes this because he doesn’t realize that he got the lowest score out of the 100 students who took the test, and that most people did quite well.
If Charles had this information, he would realize that he failed the test because he didn’t study hard enough, or because he’s not very good at biology.

On the other hand, if Charles continues to believe that the test was unfair after seeing the grade distribution, he is either severely challenged in his capacity for rational calculation or he is the perpetrator of willful ignorance.

Which is it?

unless indicated otherwise by brackets, which is the correct way to indicate this

No it isn't. The order of operations rules are at least 200 years older than the use of Brackets in Maths. Not sure how you think Maths was done before we started using Brackets.

put brackets around it or bugger off.

Bugger off with your disinformation. There are no Maths textbooks which use Brackets for such a basic expression. Students are expected to know the order of operations rules