Correction :

1 + 9 = 10	37 - 20 = 17
20 + 1 = 21	16 + 10 = 26
8 + 5 = 13	5 + 24 = 29
18 - 4 = 14	15 + 8 = 23
43 - 20 = 23	34 - 18 = 16
39 - 20 = 19	6 × 6 = 36
2 - 0 = 2	23 - 15 = 8
4 + 14 = 18	13 + 8 = 21
24 - 21 = 3	22 + 1 = 23
16 - 15 = 1	22 : 11 = 2