вариант 5
U1=U2=60 B
I1=U1/R1=60/6=10 A
I2=U2/R2=60/12=5A
I3=I4=(I1+I2)R5/(R3+R4+R5)=(10+5)12/(10+2+12)=15·12/24=7,5
U3=I3·R3=7,5·10=75 B
U4=I4·R4=7,5·2=15 B
U5=U3+U4=75+15=90 B
I5=U5/R5=90/7,5=12 B
Вариант 6
R(1-3)=R1·R2/(R1+R2)+R3=3·6/(3+6)+2=2+2=4 Ом
R(4-5)=R4·R5/(R4+R5)=12·6/(12+6)=72/18=4 Ом
R=R(1-3)·R(4-5)/[R(1-3)+R(4-5)]=4·4/(4+4)=2 Ом
I=Uаб/R=18/2=9 В