clc
clear

A = [2 -3 5 4;
     6 4 -2 7;
     9 -5 8 -3;
     11 7 3 6];

b = [18; 31; 27; 64];

solution = A\b;

x = solution(1)
y = solution(2)
z = solution(3)
w = solution(4)