We know, $$3 \frac12=3+\frac12$$
Then, if we have
$$3 \frac12 ÷ 3 \frac12$$
It means:
$a)\,\frac72 ÷ \frac72=1$ or
$b)\, 3+\frac12 ÷ 3+\frac12 =\frac{7}2$ or
$c)\, 3 + 1 ÷ 2 ÷ 3 + 1 ÷ 2=\frac{11}3$
Which one is true?
Sorry, maybe it appears on another question, but i want to make it sure between b) and c).
This is correctly read as $${3{1\over 2}\over 3{1\over 2}}=1,$$ essentially because juxtaposition always binds tighter than explicitly-written infix operations like $\div$.
However, I would rather not read it at all! Not only is the notation a bit ambiguous, but mixed-fraction notation is generally pretty unwieldy for arithmetic operations - when looking at anything more complicated than addition of fractions with the same denominator, so-called "improper fractions" are better than mixed fractions.