9. 15 – 8; 60 – 50; 6 + 6 – 10; 13 – 8; 30 + 40; 7 + 7 – 10

15 - 8 = 7

13 - 8 = 5

60 - 50 = 10

30 + 40 = 70

6 + 6 - 10 = 12 - 10 = 2

7 + 7 - 10 = 14 - 10 = 4