4. Выполни вычитание.

Решение:

1. \( 50 - 20 - 5 = 30 - 5 = 25 \)
2. \( 90 - 70 - 7 = 20 - 7 = 13 \)
3. \( 20 - 10 - 2 = 10 - 2 = 8 \)
4. \( 70 - 40 - 6 = 30 - 6 = 24 \)
5. \( 40 - 20 - 9 = 20 - 9 = 11 \)
6. \( 60 - 40 - 4 = 20 - 4 = 16 \)
7. \( 80 - 30 - 8 = 50 - 8 = 42 \)
8. \( 30 - 10 - 3 = 20 - 3 = 17 \)
9. \( 90 - 30 - 8 = 60 - 8 = 52 \)
10. \( 100 - 60 - 1 = 40 - 1 = 39 \)
11. \( 80 - 56 = 24 \)
12. \( 40 - 19 = 21 \)
13. \( 60 - 38 = 22 \)
14. \( 90 - 63 = 27 \)
15. \( 30 - 25 = 5 \)
16. \( 70 - 31 = 39 \)
17. \( 50 - 14 = 36 \)
18. \( 20 - 12 = 8 \)
19. \( 80 - 54 = 26 \)
20. \( 100 - 47 = 53 \)

Ответ: 25, 13, 8, 24, 11, 16, 42, 17, 52, 39, 24, 21, 22, 27, 5, 39, 36, 8, 26, 53.