Implied vs Explicit
I prefer to use parenthesis to clearly express the precedence. This saves me from having to mentally reestablish the precedence every time I read my own code. Also, a lesser experienced developer might go astray on this.
(25 /5) + (6 * 5) in my humble opinion, makes it clearer with little extra effort -- you DID know the evaluation order of the statement when you created it.
If you are using a more complicated formula and instead of hard-coded numbers, actual column names, the benefit is even more pronounced.
Also, the question of using 25 / 6 (instead of 25 /5) is interesting. In addition to all the precedence rules, you also have to establish the difference between
[font="Courier New"]SELECT 25 / 6 [4]
SELECT 25.0 / 6, 25.0 / 6.0 [4.166666] in both cases.[/font]
I would also code in the appropriate ROUND and CEILING or FLOOR or CONVERT()
to make it clear how to deal with integer: decimals rounded-off or truncated.