Ответ:

70 + 20 = 90

60 + 2 = 62

80 − 50 = 30

8 + 70 = 78

17 − 9 = 8

7 + 7 = 14

9 + 3 − 4 = 12 − 4 = 8

18 − 9 + 7 = 9 + 7 = 16