Решение:
1) (90 - 17) - 15 = 73 - 15 = 58
2) (84 - 16) - (18 + 40) = 68 - 58 = 10
3) (80 - 65) + (70 - 55) = 15 + 15 = 30
4) (83 - 68) + 46 = 15 + 46 = 61
5) (20 - 14) + 37 = 6 + 37 = 43
6) (23 + 35) - (38 - 10)= 58 -28= 30
Ответы: 58, 10, 30, 61, 43, 30