Correction :

33 - 12 = 21	23 - 18 = 5
19 - 9 = 10	9 × 7 = 63
34 - 15 = 19	9 + 8 = 17
16 + 10 = 26	41 - 20 = 21
5 × 7 = 35	27 - 10 = 17
30 - 17 = 13	8 + 10 = 18
8 + 21 = 29	5 + 20 = 25
21 + 7 = 28	29 - 20 = 9
18 + 10 = 28	13 - 8 = 5
22 + 10 = 32	33 - 24 = 9