Correction :

11 × 5 = 55	8 - 1 = 7
22 - 6 = 16	8 + 5 = 13
1 + 14 = 15	24 + 9 = 33
11 + 12 = 23	4 + 8 = 12
40 - 19 = 21	14 - 5 = 9
22 - 4 = 18	2 : 2 = 1
24 + 18 = 42	2 + 4 = 6
11 + 23 = 34	5 + 7 = 12
20 + 7 = 27	9 - 2 = 7
21 + 3 = 24	18 - 16 = 2