Correction :

56 : 7 = 8	14 - 11 = 3
16 + 12 = 28	30 - 22 = 8
20 : 2 = 10	24 + 12 = 36
18 + 8 = 26	15 + 15 = 30
8 + 7 = 15	15 + 21 = 36
22 + 21 = 43	26 - 13 = 13
31 - 15 = 16	3 + 20 = 23
24 - 21 = 3	18 + 9 = 27
26 - 21 = 5	26 - 5 = 21
8 + 1 = 9	35 - 18 = 17