Correction :

27 - 7 = 20	2 + 12 = 14
45 - 21 = 24	36 - 21 = 15
12 - 10 = 2	19 - 1 = 18
23 + 14 = 37	35 - 22 = 13
21 + 17 = 38	4 + 6 = 10
11 × 10 = 110	9 × 5 = 45
20 - 0 = 20	4 - 3 = 1
24 + 17 = 41	13 - 4 = 9
13 - 10 = 3	31 - 10 = 21
10 × 7 = 70	12 - 1 = 11