R1=3 R2=2 R3=8 I3=0.1
R23=2*8/(2+8)=1.6 Ro=R23+R1=4.6 U23=R3*I3=0.8 B
Io=U23/R23=0.8/1.6=0.5 A
Uo=Io*Ro=4.6*0.5=2.3 B
================================
U=4 R1=2 R2=3 R3=4=R4 R5=0.8
R12=2*3/(2+3)=1.2 R34=4/2=2
Ro=R12+R34+R5=4
Io=U/Ro=1/1=1 A
U12=Io*R12=1.2 B
I1=U12/R1=0.6 A I2=Io-I1=0.4 A I3=I4=Io/2=0.5 A
I5=Io=1 A