eps = 1e-9;

%% Triangle--Star Transformation
R1=200;
R2=300;
R3=500;
R4=100;
R5=50;
U=16;
%U=32;
%%%%%%%%%
% triangle->star
Ra=(R1*R2)/(R1+R2+R3);
Rb=(R1*R3)/(R1+R2+R3);
Rc=(R2*R3)/(R1+R2+R3);

% resistors in series
Rb4=Rb+R4;
Rc5=Rc+R5;

% resistors in parallel
Rb4c5=(Rb4*Rc5)/(Rb4+Rc5);

% resistors in series
Rekv = Ra+Rb4c5;

% overall current
I=U/Rekv;

URa=I*Ra;
URb4c5=I*Rb4c5
URb4c5=U-URa % check using II. KL

IRb4=URb4c5/Rb4;
IRc5=URb4c5/Rc5
IRc5=I-IRb4 % check using I. KL

URb=IRb4*Rb;
UR4=IRb4*R4
URc=IRc5*Rc;
UR5=IRc5*R5

% reverse voltage calculation
% II. KL
UR2=U-UR5
UR1=U-UR4
UR3=UR2-UR1

% Ohms law
IR1=UR1/R1;
IR2=UR2/R2;
IR3=UR3/R3;

% check using I. KL
% IR1==IR3+IRb4
abs(IR1-(IR3+IRb4))<eps
% IR2+IR3==IRc5
abs(IR2+IR3-IRc5)<eps