Correction :

21 + 23 = 44	2 + 4 = 6
21 - 16 = 5	1 × 11 = 11
19 - 12 = 7	19 - 2 = 17
16 + 4 = 20	9 × 7 = 63
20 + 19 = 39	28 - 12 = 16
10 × 5 = 50	11 - 3 = 8
14 + 3 = 17	25 - 3 = 22
30 - 19 = 11	8 - 0 = 8
24 : 8 = 3	70 : 10 = 7
33 - 9 = 24	21 + 21 = 42