Correction :

8 + 20 = 28	22 + 1 = 23
17 + 0 = 17	14 - 5 = 9
17 + 10 = 27	15 + 9 = 24
13 - 10 = 3	8 + 7 = 15
2 × 10 = 20	9 - 6 = 3
21 - 1 = 20	3 + 19 = 22
39 - 22 = 17	12 - 12 = 0
9 - 3 = 6	15 - 9 = 6
22 + 8 = 30	35 - 18 = 17
13 + 17 = 30	29 - 6 = 23