a)`1,15 - (-\frac{3}{10}) + 1\frac{3}{4} = 1,15 + 0,3 + 1,75 = 3,2 `

b) `(\frac{6}{11} + 3\frac{4}{9}) \cdot \frac{4}{5} - \frac{4}{5} \cdot (\frac{4}{9} + \frac{39}{11}) = \frac{4}{5} \cdot (\frac{6}{11} + \frac{31}{9} - \frac{4}{9} - \frac{39}{11}) = \frac{4}{5} \cdot (-\frac{33}{11} + \frac{27}{9}) = \frac{4}{5} \cdot (-3 + 3) = 0 `

c) `\frac{-5}{8} + 1,8 - 2\frac{5}{7} - \frac{3}{8} - \frac{4}{5} + \frac{12}{7} = (-\frac{5}{8} - \frac{3}{8}) + (1,8 - 0,8) + (-\frac{19}{7} + \frac{12}{7}) = -1 + 1 - 1 = -1 `

d) `2024 \cdot (\frac{3}{5} - 2\frac{6}{13} + 0,25) - 2024 \cdot (-3\frac{3}{4} + \frac{7}{13} + \frac{3}{5}) = 2024 \cdot [(\frac{3}{5} - \frac{3}{5}) + (-\frac{32}{13} - \frac{7}{13}) + (\frac{1}{4} + \frac{15}{4})] = 2024`