The image you uploaded contains a few problems. Here’s a brief summary of each one:

1. Bài 3 (Problem 3): This is about finding the surface area of a cube with a given square cross-sectional area of 140 cm².
2. Bài 4 (Problem 4): This is about calculating the surface area of a truncated cone (a frustum), given specific dimensions.

Would you like help solving these problems step by step? Feel free to let me know which one you want to start with!