Correction :

20 - 14 = 6	26 - 8 = 18
2 + 20 = 22	17 + 15 = 32
21 - 6 = 15	23 - 8 = 15
30 - 18 = 12	9 + 24 = 33
13 - 9 = 4	19 - 9 = 10
13 - 6 = 7	37 - 18 = 19
80 : 8 = 10	3 × 8 = 24
24 + 16 = 40	1 × 11 = 11
16 - 11 = 5	13 + 9 = 22
9 × 3 = 27	28 - 6 = 22