Correction :

28 - 17 = 11	17 - 16 = 1
2 × 6 = 12	36 - 13 = 23
25 - 21 = 4	17 + 13 = 30
27 - 23 = 4	1 + 0 = 1
22 + 8 = 30	24 + 6 = 30
8 - 0 = 8	35 - 20 = 15
13 - 2 = 11	14 - 13 = 1
0 + 21 = 21	14 - 3 = 11
4 - 2 = 2	24 - 10 = 14
2 + 21 = 23	14 + 4 = 18