R общ= ((R1+R2+R3)*(R4+R5))/((R1+R2+R3)+(R4+R5))=120000/800=150 Ом
I общ =U/R=7.5/150=0.05 A
I1=I2=I3=U/(R1+R2+R3)=7.5/600=0.0125 A
I4=I5=U/(R4+R5)=7.5/200=0.0375 A
U1=I1*R1=0.0125*100=1.25 B
U2=I1*R2=0.0125*200=2.5 B
U3=I1*R3=0.0125*300=3.75 B
U4=U5=I4*R4=0.0375*100=3.75 B