
simplification?
aa
_
a  a
_
b
not sure if that makes sense like that but im not entirely sure how to write it, basically a take away a over a take away a over b, simplified.
Would I be right to make the last part
a a
__
1 b
so it turns into 1b because the top parts cancel each other out, so I'm left with aa
_
1b?
Or is that completely on the wrong track?

Did you mean $\displaystyle \frac{aa}{\frac{aa}{b}}$?

Nope. Hmm, how to explain it.
az
_
q  y
_
b
a=z=q=y, but hopefully it gives more clarification, its a minus z over q minus y over b.
edit: nope, cant get the underscores to stay spaced out how id like ><

I think you mean:
$\displaystyle \frac{(\frac{a  z}{q  y})}{b}$, well if this is the case let's simplify it:
$\displaystyle \frac{az}{qy} \cdot \frac{1}{b}$,
$\displaystyle \frac{a  z}{(q  y) \cdot b}$
There isn't any possible way to simplify this, if I apply this to your question:
$\displaystyle \frac{\frac{aa}{aa}}{b}$,
$\displaystyle \frac{aa}{aa} \cdot \frac{1}{b}$
$\displaystyle 1 \cdot \frac{1}{b} = \frac{1}{b}$
It can't be simplified any further.
In case you have the thing that Defunkt wrote:
$\displaystyle \frac{aa}{\frac{aa}{b}}$
$\displaystyle (a  a) \cdot \frac{1}{\frac{aa}{b}}$
$\displaystyle (a  a) \cdot \frac{b}{aa} = 0 \cdot \frac{b}{0}$
not possible because we divide by $\displaystyle aa = 0$
We could've also seen this by:
$\displaystyle \frac{0}{\frac{0}{b}} = \frac{0}{0}$ (this is undefined)