Correction :

45 - 21 = 24	21 - 1 = 20
15 - 13 = 2	11 + 10 = 21
18 - 11 = 7	64 : 8 = 8
39 - 17 = 22	26 - 18 = 8
41 - 24 = 17	12 - 2 = 10
21 + 11 = 32	70 : 10 = 7
2 + 0 = 2	19 - 15 = 4
30 - 19 = 11	1 × 8 = 8
25 - 24 = 1	6 - 1 = 5
39 - 18 = 21	3 + 12 = 15