3. 600-(80-25) 100: (172-18.4)

1) 600 - (80 - 25) = 600 - 55 = 545
2) 100 : \(172 - 18 \cdot 4\) = 100 : (172 - 72) = 100 : 100 = 1

Ответ: 1) 545; 2) 1