Given the matrices A=[[2, 1, 1], [3, -1, 0], [0, 2, 4]], B=[[9, 7, -1], [3, 5, 4], [2, 1, 6]] and C=[[2, -4, 3], [1, -1, 0], [9, 4, 5]] Verify that (A+B)+C=A+(B+C).