Correction :

5 × 10 = 50	6 - 5 = 1
16 + 12 = 28	29 - 17 = 12
11 - 6 = 5	36 - 17 = 19
7 - 1 = 6	25 - 3 = 22
12 + 9 = 21	20 : 4 = 5
40 : 4 = 10	4 × 1 = 4
2 + 9 = 11	11 + 12 = 23
43 - 19 = 24	37 - 14 = 23
30 : 6 = 5	66 : 6 = 11
34 - 13 = 21	27 - 22 = 5