canceling double fractions how?I had this example: 11 5 2 = 11 10 then: 2...

I always regarded the triple (or quadruple) fraction notation to be confusing and wrong, so instead (even to this day) I always make myself read fractions like this:
The fraction $\frac{\frac{a}{b}}{c}$ is equivalent to $\frac{a}{b}÷c$ and therefore $\frac{a}{b}\times \frac{1}{c}=\frac{a}{bc}$. For quadruples it works the same: $\frac{\frac{a}{b}}{\frac{c}{d}}=\frac{a}{b}÷\frac{c}{d}=\frac{a}{b}\times \frac{d}{c}=\frac{ad}{bc}$
So using this I would say $\frac{\frac{11}{5}}{2}=\frac{11}{5}\times \frac{1}{2}=\frac{11}{10}$

No, it isn't. Multiplying
$\frac{\frac{11}{5}}{2}$
by
$\frac{5}{5}(=1)$
gives you
$\frac{\frac{11}{5}}{2}=\frac{\frac{11}{5}}{2}\cdot \frac{5}{5}=\frac{\frac{11}{5}\cdot 5}{2\cdot 5}=\frac{11}{10}.$