Vòng 3 - Vòng chung khảo

2) C

3) B

4) Swap it: 80%

5) \(6\sqrt{6}\)

6) 

7) a.

    b. 20

    c. 1

8) https://drive.google.com/file/d/1Pg5FX3OqDQDGdA_VZ7BBUTPSJ2egNyai/view?usp=sharing