Sorry Ingrid ,
I've got another questions because is not enought clear for me.
This is the raglan decrease for back:
RS:-K.2,K.2tog.,k.to last 4 sts.,sl.1,k.1,p.s.s.o.,k.2.
if i have to decrease 1 st at the same time at neck edge , that means that i will decrease twice because the neck edge will always be decreased following the raglan decrease as given for back.
i hope it is clear what i wrote down, if not i'll try to make it clear.