Correction :

36 - 13 = 23	19 + 17 = 36
21 + 21 = 42	3 + 9 = 12
5 × 5 = 25	20 + 10 = 30
30 : 5 = 6	18 - 10 = 8
4 - 1 = 3	23 - 11 = 12
12 + 0 = 12	26 - 17 = 9
22 - 5 = 17	41 - 19 = 22
20 + 11 = 31	2 + 18 = 20
2 + 3 = 5	0 + 2 = 2
15 - 12 = 3	15 + 4 = 19