Dear Fotis,
That question I ask Saturn and he replied already. I am sorry if you misunderstand that I asked you.

Dear Saturn,
May your need is:

IF(E4*G4*I4=0,"",(D4*(E4>0)+F4*(G4>0)+H4*(I4>0))/(IF(E4>0,D4/E4,0)+IF(G4>0,F4/G4,0)+IF(I4>0,H4/I4,0)))

It means the formula ignore blank cells within E4, G4, I4, and calculate the rests.

(Divide by and multiply with what you want)