Correction :

12 - 9 = 3	13 + 8 = 21
9 + 15 = 24	14 + 8 = 22
7 : 1 = 7	3 × 4 = 12
30 - 8 = 22	27 - 20 = 7
22 : 11 = 2	17 - 17 = 0
6 + 9 = 15	16 - 16 = 0
6 + 2 = 8	25 - 6 = 19
28 - 19 = 9	37 - 18 = 19
22 + 22 = 44	5 + 15 = 20
19 + 10 = 29	12 + 20 = 32