1) 12-6+7=, 13-5-4=, 2) 19-(17-8)=, 15-(9+6)=

Решение:

1. 1) \(12 - 6 + 7 = 13\)
   \(13 - 5 - 4 = 4\)
2. 2) \(19 - (17 - 8) = 19 - 9 = 10\)
   \(15 - (9 + 6) = 15 - 15 = 0\)

Ответ: 1) 13, 4; 2) 10, 0