8. Вычисли. 20.40:40.2= 60:20:60:30= 40:20:80:40= 20.30:30.2=

Решение:

1. \( 20 \cdot 40 : 40 \cdot 2 = 800 : 40 \cdot 2 = 20 \cdot 2 = 40 \)
2. \( 60 : 20 : 60 : 30 = 3 : 60 : 30 = \frac{1}{20} : 30 = \frac{1}{600} \)
3. \( 40 : 20 : 80 : 40 = 2 : 80 : 40 = \frac{1}{40} : 40 = \frac{1}{1600} \)
4. \( 20 \cdot 30 : 30 \cdot 2 = 600 : 30 \cdot 2 = 20 \cdot 2 = 40 \)

Ответ: 40; \(\frac{1}{600}\); \(\frac{1}{1600}\); 40.