Correction :

36 - 18 = 18	20 + 23 = 43
21 + 21 = 42	70 : 7 = 10
13 - 3 = 10	9 + 14 = 23
77 : 11 = 7	0 + 4 = 4
11 × 3 = 33	4 + 15 = 19
2 + 20 = 22	19 - 19 = 0
6 + 7 = 13	25 - 18 = 7
3 + 17 = 20	0 + 5 = 5
10 : 5 = 2	4 + 23 = 27
28 - 15 = 13	17 + 3 = 20