Correction :

33 - 23 = 10	18 : 9 = 2
7 + 18 = 25	5 × 9 = 45
18 + 18 = 36	16 + 15 = 31
16 + 8 = 24	19 - 7 = 12
35 - 15 = 20	6 + 21 = 27
18 + 4 = 22	21 + 10 = 31
3 + 3 = 6	16 + 6 = 22
19 + 8 = 27	55 : 11 = 5
20 + 7 = 27	28 - 15 = 13
30 - 8 = 22	10 × 5 = 50