1) 2,25+0,75:(0,8*2,25-0,615:0,3)= 2) - 0,03*(-5/9):(1,53:1,5-1,2)+1= 3) (0,4-2,38-3,452):4 1/2-2 4/9=

Решение:

1. \(2,25 + 0,75 : (0,8 \cdot 2,25 - 0,615 : 0,3)\)
   \( = 2,25 + 0,75 : (1,8 - 2,05)\)
   \( = 2,25 + 0,75 : (-0,25)\)
   \( = 2,25 - 3\)
   \( = -0,75 \)
2. \(-0,03 \cdot \left(-\frac{5}{9}\right) : (1,53 : 1,5 - 1,2) + 1\)
   \( = \frac{3}{100} \cdot \frac{5}{9} : (1,02 - 1,2) + 1\)
   \( = \frac{1}{60} : (-0,18) + 1\)
   \( = \frac{1}{60} : \left(-\frac{18}{100}\right) + 1\)
   \( = \frac{1}{60} \cdot \left(-\frac{100}{18}\right) + 1\)
   \( = -\frac{100}{1080} + 1\)
   \( = -\frac{5}{54} + 1\)
   \( = \frac{49}{54} \)
3. \((0,4 - 2,38 - 3,452) : 4\frac{1}{2} - 2\frac{4}{9}\)
   \( = (-1,98 - 3,452) : \frac{9}{2} - \frac{22}{9}\)
   \( = -5,432 : \frac{9}{2} - \frac{22}{9}\)
   \( = -5,432 \cdot \frac{2}{9} - \frac{22}{9}\)
   \( = -\frac{10,864}{9} - \frac{22}{9}\)
   \( = -\frac{32,864}{9}\)

Ответ: 1) -0,75; 2) 49/54; 3) -32,864/9.