V1=12;                     //Assigning values to parameters
V2=8;
I1=4;
R1=2;
R2=10;
R3=20;
R4=5;
R5=15;
R6=25;
R7=5;
A=[1,-1,0;-12,-20,15;0,15,-45];   //Current coeffecients
B=[4;-12;8];
I=inv(A)*B;
Vth=V1-R1*I(1,1)-R2*I(1,1);     //Thevenin voltage
Ra=R1+R2;
Rb=R6+R7;
Rc=(R5*Rb)/(R5+Rb);
Rd=R4+Rc;
Rth=(Ra*Rd)/(Ra+Rd);          //Thevenin resistance
Il=Vth/(R3+Rth);
P=Il*Il*R3;
disp("Watts",P,"Power drawn by 20 Ohm resistor");