clear;
clc;
a=.26;
b=.15;
c=.35;
y=[(1+b) b;-(1+a) (1+c)];
z=[1+a;a];
v=round(inv(y)*z*1e3)*1e-3; 
t=v(1,1);
u=v(2,1);
n=(t+u+1)/(3*u);
mprintf("the string efficiency is =%.2f",n);