4 5 x 9 4 2 x 6 9 July 8, 2019 16 32 64 128 4 5 x 9 4 2 x 6 9 2 10 x 3 8 6 8 x 20 4 mũ 5 x 9 mũ 4 trừ 2 x 6 mũ 9 4 x 9 - 5
