I built DMux4Way using 2 Not gates and 8 And gates. I couldn't built it using DMux gate.
by this method DMux8Way will require 4 Not gates and 12 And gates. So? Could it be built in a better way or is this fine ?
We don't encourage just showing people the solutions. That really detracts from the learning opportunities that struggling with doing it yourself provides. It can be frustrating, but it is an excellent way to actually learn.
Your code in your other thread (which is the best place to continue the discussion) is on the right track. So I'll offer some suggestions to help you move forward over there.