1) \(\frac{4}{25} + \frac{15}{4} = \frac{4 \cdot 4 + 15 \cdot 25}{100} = \frac{16 + 375}{100} = \frac{391}{100} = 3 \frac{91}{100} = 3,91\)
2) \(\frac{9}{4} + \frac{8}{5} = \frac{9 \cdot 5 + 8 \cdot 4}{20} = \frac{45 + 32}{20} = \frac{77}{20} = 3 \frac{17}{20}\)
3) \(\frac{1}{2} - \frac{9}{25} = \frac{1 \cdot 25 - 9 \cdot 2}{50} = \frac{25 - 18}{50} = \frac{7}{50}\)
4) \(\frac{11}{4} - \frac{2}{5} = \frac{11 \cdot 5 - 2 \cdot 4}{20} = \frac{55 - 8}{20} = \frac{47}{20} = 2 \frac{7}{20}\)
Ответ: 1) \(3,91\); 2) \(3 \frac{17}{20}\); 3) \(\frac{7}{50}\); 4) \(2 \frac{7}{20}\)