1. \(\frac{2}{3} \cdot \frac{4}{5}\) 2. \(1\frac{1}{2} \cdot 0.4\) 3. \(0.25 \cdot \frac{8}{9}\) 4. \(\frac{5}{8} \cdot \frac{4}{15}\) 5. \(2\frac{1}{4} \cdot 1.2\) 6. \(3.5 \cdot 1\frac{3}{7}\)

Решение:

1. \(\frac{2}{3} \cdot \frac{4}{5} = \frac{2 \cdot 4}{3 \cdot 5} = \frac{8}{15}\)
2. \(1\frac{1}{2} \cdot 0.4 = \frac{3}{2} \cdot \frac{4}{10} = \frac{3}{2} \cdot \frac{2}{5} = \frac{3 \cdot 2}{2 \cdot 5} = \frac{6}{10} = \frac{3}{5}\)
3. \(0.25 \cdot \frac{8}{9} = \frac{1}{4} \cdot \frac{8}{9} = \frac{1 \cdot 8}{4 \cdot 9} = \frac{8}{36} = \frac{2}{9}\)
4. \(\frac{5}{8} \cdot \frac{4}{15} = \frac{5 \cdot 4}{8 \cdot 15} = \frac{20}{120} = \frac{1}{6}\)
5. \(2\frac{1}{4} \cdot 1.2 = \frac{9}{4} \cdot \frac{12}{10} = \frac{9}{4} \cdot \frac{6}{5} = \frac{9 \cdot 6}{4 \cdot 5} = \frac{54}{20} = \frac{27}{10} = 2.7\)
6. \(3.5 \cdot 1\frac{3}{7} = \frac{35}{10} \cdot \frac{10}{7} = \frac{7}{2} \cdot \frac{10}{7} = \frac{7 \cdot 10}{2 \cdot 7} = \frac{70}{14} = 5\)

Ответ: 1. \(\frac{8}{15}\); 2. \(\frac{3}{5}\); 3. \(\frac{2}{9}\); 4. \(\frac{1}{6}\); 5. \(2.7\); 6. \(5\).