Solution:

Let $3 x(n)+3.6 x(n-1)+0.6 x(n-2)=w(n)$

$ y(n)=-0.1 y(n-1)+0.2 y(n-2)+\omega(n) .\\ $

Direct from,

$ A(z)=\frac{Y(z)}{X(z)}=\frac{3+3.6 z^{-1}+0.6 z^{-2}}{1+0.1 z^{-1}-0.2 z^{-2}}\\ $

Cascade form,

$ \begin{aligned}\\ &H(z)=\frac{\left(3+0.6 z^{-1}\right)\left(1+z^{-1}\right)}{\left(1+0.5 z^{-1}\right)\left(1-0.4 z^{-1}\right)} \\\\ &H_1(z)=\frac{3+0.6 z^{-1}}{1+0.5 z^{-1}} \text { and } H_2(z)=\frac{1+z^{-1}}{1-0.4 z^{-1}} .\\ \end{aligned}\\ $

Parallel form.

$ H(z)=-3+\frac{7}{1-0.4 z^{-1}}+\frac{1}{1+0.5 z^{-1}}\\ $