Correction :

3 + 9 = 12	30 - 11 = 19
13 - 10 = 3	25 - 18 = 7
13 - 5 = 8	13 + 15 = 28
16 - 4 = 12	36 - 24 = 12
42 - 21 = 21	14 : 7 = 2
16 + 7 = 23	10 + 12 = 22
37 - 13 = 24	14 - 12 = 2
16 - 2 = 14	3 + 19 = 22
24 - 15 = 9	37 - 21 = 16
23 - 7 = 16	26 - 16 = 10