Correction :

10 + 18 = 28	21 - 2 = 19
16 - 12 = 4	25 - 2 = 23
14 - 3 = 11	29 - 12 = 17
7 + 5 = 12	9 - 6 = 3
9 - 8 = 1	4 × 9 = 36
42 : 6 = 7	21 : 3 = 7
7 × 11 = 77	30 - 14 = 16
16 + 8 = 24	14 + 7 = 21
50 : 10 = 5	27 - 8 = 19
16 - 14 = 2	22 : 11 = 2