E1 = 5;
E2 = 10;
E3 = 15;
E4 = 20;
E5 = 25;
I1 = 10;
Y1 = 5;
Y2= 7;
Y3=10;
Y4= 15;
Y5=13;
Y6=14;
Y7=20;

C = [1*Y2 + 1*Y3 + 1*Y4, -1*Y2, -1*Y3; -1*Y2, 1*Y6+1*Y2+1*Y1, -1*Y1; -1*Y3,-1*Y1,1*Y7+1*Y5+1*Y3+1*Y1];

B= [-I1 + E5*Y4; E1*Y1 + E2*Y6; -E1*Y1 - E3*Y5 + E4*Y7];

V = inv(C) * B

VB = V(1)
VC = V(2)
VD = V(3)

I4 = (VD  - E4)*Y7
I3 = (VD  + E3)*Y5
I6 = (VD - VB)*Y3
I8 = (VC - VD - E1)*Y1
I2 =(-VC + E2)*Y6
I5 =(VB - E5)*Y4
I7 = (VC - VB)*Y2

D = I8 - I6 - I3 - I4
C = -I8 - I7 + I2
B = I7 + I6 -I1 - I5
A = -I2 + I5 + I1 + I3 + I4