How to write "percentage" answers (US)

UPDATE.... The response from u/educational_two682 resolved my question. Thanks again.

I've been out of school for 50 years, and I don't do modern tests and math assignments myself. But sometimes I help students who do. So, I am wondering what are acceptable ***forms*** of answers in the following situation. Note: I am asking from an American perspective, if that matters.

\[EDIT.... I have limited my question to just algebraic answers. Thanks to u/master-education7076 for noting additional ambiguities with my now-removed numerical examples. That was not my intended focus.\]

Consider a recent algebra problem. We calculate that x-65 employees are in one category out of a total of 2x-65 employees, and the question is: what percentage *\[sic\]* of the total are in that category?

All of the following ***forms*** are equivalent mathematically: (x-65) / (2x-65) ; ( 100\*(x-65) / (2x-65) )% ; and 100\*(x-65)% / (2x -65).

But again, is only one ***form*** allowed? Is one ***form*** preferred? Or are they all equally acceptable ***forms***?

Aside.... I have even seen c. Note the space before "%" and the absence of disambiguating parentheses. Mathematicians probably have no issue with that form because "%" should be interpreted as "/ 100", so standard math should parse that as

( ( 100*(x-65) ) / (2x-65) )%

But Excel, Google Sheets et al parse 100\*(x-65) / (2x-65) % as

( ( 100*(x-65) ) / ( (2x-65)% )

Let's not digress. It is what it is.

But for completeness, is 100\*(x-65) / (2x-65) % without disambiguating parentheses allowed? Preferred? Acceptable?