Correction :

42 - 24 = 18	7 × 5 = 35
15 + 3 = 18	34 - 15 = 19
10 × 3 = 30	7 × 6 = 42
2 + 10 = 12	21 + 0 = 21
44 - 20 = 24	36 : 4 = 9
4 + 7 = 11	11 + 14 = 25
11 + 20 = 31	41 - 24 = 17
17 - 12 = 5	2 + 1 = 3
10 + 8 = 18	33 - 15 = 18
5 - 1 = 4	34 - 24 = 10