Correction :

45 - 24 = 21	19 + 9 = 28
19 - 10 = 9	3 - 0 = 3
18 + 19 = 37	5 - 5 = 0
37 - 18 = 19	40 - 22 = 18
5 + 20 = 25	6 × 3 = 18
0 + 14 = 14	43 - 19 = 24
16 : 4 = 4	1 × 1 = 1
11 - 10 = 1	18 - 12 = 6
18 - 6 = 12	27 - 19 = 8
20 + 11 = 31	25 - 21 = 4