Correction :

5 - 0 = 5	16 + 11 = 27
13 - 9 = 4	20 + 2 = 22
15 + 24 = 39	4 + 16 = 20
33 - 13 = 20	19 + 4 = 23
23 + 4 = 27	17 - 8 = 9
6 + 10 = 16	24 - 6 = 18
15 + 8 = 23	11 + 21 = 32
27 - 4 = 23	17 + 22 = 39
22 + 1 = 23	30 - 23 = 7
20 - 13 = 7	77 : 11 = 7