Выразите обыкновенной дробью: 26%; 45%; 80%; 90%.

Решение:

1. 26% = \(\frac{26}{100} = \frac{13}{50}\)
2. 45% = \(\frac{45}{100} = \frac{9}{20}\)
3. 80% = \(\frac{80}{100} = \frac{4}{5}\)
4. 90% = \(\frac{90}{100} = \frac{9}{10}\)

Ответ: \(\frac{13}{50}\); \(\frac{9}{20}\); \(\frac{4}{5}\); \(\frac{9}{10}\).