Correction :

35 - 11 = 24	19 - 8 = 11
16 + 8 = 24	4 + 24 = 28
21 - 13 = 8	3 - 3 = 0
29 - 11 = 18	20 : 10 = 2
5 + 1 = 6	18 - 18 = 0
8 + 15 = 23	23 + 6 = 29
21 + 20 = 41	11 + 11 = 22
13 + 15 = 28	4 + 14 = 18
14 + 12 = 26	23 - 5 = 18
15 + 11 = 26	20 : 2 = 10