Correction :

37 - 20 = 17	21 - 12 = 9
28 - 13 = 15	16 - 3 = 13
24 - 14 = 10	25 - 24 = 1
20 + 1 = 21	8 + 9 = 17
36 - 14 = 22	28 - 24 = 4
23 + 14 = 37	34 - 16 = 18
20 - 15 = 5	63 : 9 = 7
8 + 0 = 8	9 + 8 = 17
14 - 1 = 13	100 : 10 = 10
2 + 1 = 3	39 - 20 = 19