A = [[5, 2, -4, 0],
     [1, 0, 3, -6],
     [1, 1, -3, 1],
     [3, -2, 0, 2]]

b = [3, -2, 0, 3]

# solution [1, 1, 1, 1]

A = [[1, 2, 3],
     [2, 4, 6],
     [1, 1, 1]]

b = [6, 10, 3]

#no solution