To be fair though, even if you write it as 48/2(9+3), I think there is a tendency in the sciences to give priority to what’s called “implicit” multiplication in @halabihazem‘s link.
Whether the same can be said about mathematicians, I don’t know.
Either way, as I said, it’s a great example of the limitations of standard word-processing. Nobody would ever write something like that on paper; the priority would be obvious from whether the (9+3) was part of the denominator, or to the right of the whole fraction.
You have to use a lot of brackets, if you want in-line expressions to be unambiguous.
This often results in something very difficult to read, however. Practically useless in a report. I don’t thank Microsoft very often, but the equation editor in the new versions of Word saves a lot of time for me.