I4=I=3 А. R23=R2+R3=7+9=16 Ом. Rэкв=R4+R1*R23/(R1+R23)=3+48*16/(48+16)=15 Ом.U4=I4*R4=3*3=9 В.R123=R1*R23/(R1+R23)=48*16/(48+16)=12 Ом.U1=U123=I*R123=3*12=36 В.I1=U1/R1=36/48=0,75 АI2=U123/(R2+R3)=36/(7+9)=2,25 А.U2=I2*R2=2,25*7=15,75 В U3=I2*R3=2,25*9=20,25 В.