If you would define non-equal division, you would need to specify in what way you would like to divide.
It would mean something like divide $n$ apples to Tom and Jerry in some non-equal ratio, say ratio $x:y$, then the $x$ and $y$ fraction assumes equal division.
The non-equal division is naturally explained through equal division.
Hence instead of saying divide $n$ apples among Tom and Jerry in the $1:1$ ratio, we would say divide $n$ apples among Tom and Jerry equally.
But we do not include the word "equally" since equal division is naturally assumed unless specified otherwise. This might also be something we humans agreed on mutually. Thus, we just say divide $n$ apples among Tom and Jerry.
Writing that as $n/2$.
Where on the other hand, non-equal division needs you to define how you would like to divide. Can't say give all to Tom (no division takes place) or something like "give a lot to Tom" because you need to specify what is "a lot" in some way.
If you do not specify the way to divide, there is only one way to divide it, something we all agreed on, and that's to divide it equally. And that's because it makes sense mathematically when referencing multiplication, as seen in Peter's answer.
If it would have been a specified division in a $x:y$ ratio, we would write that Tom and Jerry get respectively:
$$ \frac{n}{x+y}\times x, \frac{n}{x+y}\times y$$
Where you again see that these fractions assume equal division. Non-equal division is noted by the equal division, and equal division is, well, just division as we defined it.
I guess I need to explain ratios to you now.
Story example using non-equal division could be something like divide $12$ apples among the two brothers, where the older brother gets twice as much as the younger brother.
Our ratio is $1$ to $2$, which we write $1:2$ or $1/2$.
That's because for each one that the younger brother gets, older one gets twice as much, and that's two.
Then when using $12$ apples, for each $4$ the younger one gets, older one gets $4\times 2 = 8$, it's divided in ratio of $4:8$, divide both numbers by $4$ to get $1:2$.
$4$ to $8$ is actually $1:2$ but stacked $4$ times to reach $12$.
When dividing one to twice as much, 1:2, then $\frac{12}{1+2}=4$ gives
us the number of times we need to stack, and we just stack the ratio
then, $(1\times4 ): (2\times4) = 4:8$.
You can have a third brother which gets $3$ times as much as the youngest. If we give the smallest number of items to the youngest, he gets $1$. second one twice as much, $2$, third one three times as much as the first one, $3$. We have a $1:2:3$ ratio that we can stack.
Notice that $1+2+3=6$, we can divide $6$ apples at a time.
Thus, you can stack up these ratios and divide them if you have $6,12,18,...$ apples.
Stacking it twice gives $2:4:6$, which is the number of apples each brother gets.
Dividing just $12$ apples among two brothers equally, is like dividing
$2$ at a time to make sure everyone has the same amount at each step.
We stack the $1:1$ ratio $6$ times because $\frac{12}{1+1}=6$, to get
$(1\times6):(1\times6) = 6:6$, each one gets $6$.
For three brothers, it's $3$ at a time in $1:1:1$ ratio, which you can stack $4$ times, hence all get $4$ since we have $4:4:4$ and all apples are used: $4+4+4=12$
