2 7 6 6X X X 27 6 6X X X 7 6 6 0.25 ...
Bài 1
2
7 6 6x x x 7 6 6 0.25 8 12 0x x6 0 0.25 x2 6 60.25 0 2
7 6 6x x x 7 6 6 0.25 8 12 0x x6 0 0.25 x2 6 60.25 0