Correction :

40 - 23 = 17	21 + 18 = 39
46 - 22 = 24	36 : 9 = 4
6 - 3 = 3	0 + 2 = 2
7 - 4 = 3	44 : 4 = 11
18 + 4 = 22	12 + 5 = 17
7 + 11 = 18	17 - 11 = 6
16 + 11 = 27	20 - 1 = 19
24 + 19 = 43	37 - 17 = 20
10 - 8 = 2	11 - 3 = 8
24 : 8 = 3	41 - 22 = 19