100-85 High Distinction (A+)
84-75 Distinction (A)
74-65 Credit (B)
64-50 Pass (C)
<49 Fail (F)
That's the general percentages for Australia, though, it can depend on the university or school.
At primary school, at least at DS', there's no A+ (just an A).
Mine in NZ were much like that. National exams were often scaled to a bell curve with at 50% mean. I have never met anyone who got 10O% except in something like a lab quiz and multi choice is not commonly used although there may be a section that has it.
Oh we had A+, A, A-, B+,B, B-, C+, D.
Primary schools don't have grades and I am not sure high schools do now as the new system works in ways I don't undestand.