It is correct. StyleCop basically assumes you are not too comfortable with Operator precedence and wants that explicitly written out. That can lead to more stable code if someone works on the formulas later. Iti s technically not needed - but then you assume to be absolutely correct in your assumptions how the Compiler will handle that. Naturally that normally is the case (BODMAS).
At the end, it is a case of "you may not know what you do, so we make sure you spell that out". It is not a bad attitude - code stability IS The main concern - but you could as well just turn that warning off.