Correction :

15 + 4 = 19	25 - 1 = 24
23 + 14 = 37	8 + 2 = 10
19 - 18 = 1	22 - 18 = 4
12 + 19 = 31	42 - 21 = 21
6 + 18 = 24	21 - 0 = 21
4 - 0 = 4	17 + 9 = 26
0 + 24 = 24	2 × 3 = 6
42 - 22 = 20	2 + 19 = 21
15 + 12 = 27	26 - 11 = 15
7 + 1 = 8	36 - 19 = 17