Correction :

4 + 11 = 15	23 + 16 = 39
2 × 8 = 16	28 - 9 = 19
19 - 18 = 1	27 - 15 = 12
17 + 7 = 24	22 + 22 = 44
18 + 14 = 32	8 + 13 = 21
34 - 21 = 13	28 - 20 = 8
4 : 1 = 4	5 - 3 = 2
1 + 4 = 5	35 - 16 = 19
9 + 24 = 33	11 + 0 = 11
16 + 17 = 33	11 : 1 = 11