Correction :

9 + 7 = 16	44 - 23 = 21
80 : 10 = 8	10 + 5 = 15
2 + 24 = 26	30 - 9 = 21
3 + 13 = 16	28 - 10 = 18
9 × 9 = 81	21 - 20 = 1
13 + 6 = 19	39 - 23 = 16
21 + 12 = 33	34 - 20 = 14
9 + 21 = 30	15 + 8 = 23
9 - 2 = 7	11 + 15 = 26
12 : 4 = 3	16 + 17 = 33