Correction :

30 - 24 = 6	35 - 24 = 11
13 - 10 = 3	19 - 17 = 2
24 - 23 = 1	5 + 21 = 26
31 - 10 = 21	1 × 11 = 11
23 - 23 = 0	16 : 4 = 4
6 + 15 = 21	21 - 7 = 14
24 : 8 = 3	32 - 8 = 24
12 + 15 = 27	47 - 24 = 23
6 + 18 = 24	6 + 16 = 22
30 - 7 = 23	9 + 2 = 11