Correction :

35 - 18 = 17	5 - 3 = 2
12 - 8 = 4	16 + 2 = 18
15 - 12 = 3	66 : 11 = 6
31 - 8 = 23	10 + 21 = 31
35 : 7 = 5	45 - 24 = 21
7 + 9 = 16	46 - 23 = 23
16 + 7 = 23	25 - 14 = 11
24 + 15 = 39	11 × 9 = 99
20 - 16 = 4	32 - 23 = 9
5 - 5 = 0	23 + 14 = 37