Write function for control system block

1. The problem statement, all variables and given/known data

Write function for control system block

2. Relevant equations







3. The attempt at a solution

4 and D are parallel so we add them :

I am stucking in the simplication of this block

Should I group these elements to a function called w[nT], so

y[nT]/x[nT]=1/(1-0.1w[nT])



and by my reduction w[nT]=2(4+D), is it correct ?