R1=U1/I1=2V/0.2A=10欧
R滑=U滑/I1=(U-U1)/I1=(6V-2V)/0.2A=20欧
I1'=U/R1=6/10=0.6A
I2'=I-I1'=0.9A-0-6A=0.3A
R2=U/I2'=20欧