Correction :

23 + 13 = 36	5 : 5 = 1
6 : 1 = 6	43 - 20 = 23
0 + 7 = 7	31 - 16 = 15
18 : 3 = 6	34 - 13 = 21
19 - 4 = 15	11 × 3 = 33
29 - 8 = 21	30 - 21 = 9
16 + 23 = 39	23 + 16 = 39
20 + 15 = 35	15 - 9 = 6
13 - 7 = 6	40 : 5 = 8
7 + 5 = 12	9 - 8 = 1