Correction :

5 + 18 = 23	11 - 7 = 4
1 + 13 = 14	99 : 9 = 11
29 - 13 = 16	15 + 10 = 25
31 - 18 = 13	9 × 11 = 99
3 + 3 = 6	11 - 6 = 5
24 - 23 = 1	29 - 14 = 15
8 + 4 = 12	8 × 5 = 40
43 - 21 = 22	8 : 1 = 8
18 + 0 = 18	24 + 7 = 31
16 - 12 = 4	29 - 6 = 23