import numpy as np
import math

A = [[-2, 3.01, 0.12, -0.11], [2.92, -0.17, 0.11, 0.22], [0.66, 0.52, 3.17, 2.11], [3.01, 0.42, 0.27, -0.15]]

b = [0.2, 0.1, 0, -0.1]

def Goose(A, b):
    for i in range(4):
        for c in range(i + 1, 4):
            k = A[c][i] / A[i][i]
            b[c] -= k * b[i]
            for j in range(4):
                A[c][j] -= k * A[i][j]

Goose(A, b)

x1 = b[3] / A[3][3]
x2 = (b[2] - A[2][3] * x1) / A[2][2]
x3 = (b[1] - A[1][3] * x1 - A[1][2] * x2) / A[1][1]
x4 = (b[0] - A[0][3] * x1 - A[0][2] * x2 - A[0][1] * x3)

print("x1 =", x4)
print("x2 =", x3)
print("x3 =", x2)
print("x4 =", x1)