Correction :

15 + 10 = 25	4 × 10 = 40
1 + 0 = 1	15 + 1 = 16
40 - 21 = 19	7 + 19 = 26
6 : 6 = 1	4 × 5 = 20
14 - 12 = 2	12 + 7 = 19
12 - 8 = 4	5 - 3 = 2
36 - 12 = 24	6 × 5 = 30
29 - 7 = 22	44 - 23 = 21
43 - 24 = 19	10 + 6 = 16
1 + 4 = 5	2 + 3 = 5