Вариант 3: 1. \(\frac{4}{5} - \frac{3}{10}\) 2. \(\frac{1}{2} - \frac{4}{25}\) 3. \(\frac{13}{15} + \frac{1}{5}\) 4. \(\frac{7}{15} + \frac{4}{45}\) 5. \(\frac{9}{10} - \frac{7}{15} + \frac{4}{45}\)

Решение:

• 1. \(\frac{4}{5} - \frac{3}{10} = \frac{8}{10} - \frac{3}{10} = \frac{5}{10} = \frac{1}{2}\)
• 2. \(\frac{1}{2} - \frac{4}{25} = \frac{25}{50} - \frac{8}{50} = \frac{17}{50}\)
• 3. \(\frac{13}{15} + \frac{1}{5} = \frac{13}{15} + \frac{3}{15} = \frac{16}{15}\)
• 4. \(\frac{7}{15} + \frac{4}{45} = \frac{21}{45} + \frac{4}{45} = \frac{25}{45} = \frac{5}{9}\)
• 5. \(\frac{9}{10} - \frac{7}{15} + \frac{4}{45} = \frac{81}{90} - \frac{42}{90} + \frac{8}{90} = \frac{47}{90}\)

Ответ: 1. \(\frac{1}{2}\), 2. \(\frac{17}{50}\), 3. \(\frac{16}{15}\), 4. \(\frac{5}{9}\), 5. \(\frac{47}{90}\)