Correction :

41 - 23 = 18	13 + 12 = 25
27 - 13 = 14	32 - 23 = 9
20 + 14 = 34	23 + 14 = 37
31 - 13 = 18	15 + 3 = 18
44 : 4 = 11	21 - 8 = 13
21 - 18 = 3	12 + 20 = 32
22 + 10 = 32	22 - 22 = 0
17 - 5 = 12	7 + 14 = 21
12 + 15 = 27	23 + 18 = 41
16 + 8 = 24	16 + 17 = 33