Correction :

20 + 15 = 35	30 : 6 = 5
17 - 3 = 14	17 + 0 = 17
13 - 5 = 8	23 - 16 = 7
10 - 3 = 7	21 + 11 = 32
13 + 5 = 18	21 - 5 = 16
7 + 15 = 22	26 - 16 = 10
22 - 19 = 3	16 + 2 = 18
9 + 1 = 10	4 + 1 = 5
18 + 12 = 30	23 - 15 = 8
21 + 8 = 29	17 + 7 = 24