а) \( 5 \frac{1}{3} - 2 \frac{1}{4} \cdot \frac{4}{5} = \frac{16}{3} - \left( \frac{9}{4} \cdot \frac{4}{5} \right) = \frac{16}{3} - \frac{36}{20} = \frac{16}{3} - \frac{9}{5} = \frac{80}{15} - \frac{27}{15} = \frac{53}{15} \).
б) \( 2 \frac{2}{5} \cdot \left( 3 \frac{2}{5} - 1 \frac{11}{15} \right) = \frac{12}{5} \cdot \left( \frac{17}{5} - \frac{26}{15} \right) = \frac{12}{5} \cdot \left( \frac{51}{15} - \frac{26}{15} \right) = \frac{12}{5} \cdot \frac{25}{15} = \frac{12}{5} \cdot \frac{5}{3} = \frac{60}{15} = 4 \).