Correction :

38 - 21 = 17	15 + 3 = 18
7 + 16 = 23	24 + 6 = 30
9 - 8 = 1	43 - 23 = 20
24 : 4 = 6	13 + 20 = 33
20 + 17 = 37	6 + 10 = 16
40 - 21 = 19	41 - 18 = 23
27 - 21 = 6	41 - 18 = 23
14 + 6 = 20	32 - 8 = 24
11 - 10 = 1	28 - 17 = 11
37 - 19 = 18	21 - 18 = 3