Вычислим произведения:
а) \(4 \cdot \frac{3}{5} = \frac{4 \cdot 3}{5} = \frac{12}{5} = 2\frac{2}{5}\)
б) \(\frac{2}{3} \cdot \frac{5}{8} = \frac{2 \cdot 5}{3 \cdot 8} = \frac{10}{24} = \frac{5}{12}\)
в) \(\frac{11}{4} \cdot \frac{4}{11} = \frac{11 \cdot 4}{4 \cdot 11} = \frac{44}{44} = 1\)
г) \(\frac{21}{8} \cdot \frac{13}{14} = \frac{21 \cdot 13}{8 \cdot 14} = \frac{3 \cdot 13}{8 \cdot 2} = \frac{39}{16} = 2 \frac{7}{16}\)
д) \(\frac{2}{11} \cdot \frac{3}{4} = \frac{2 \cdot 3}{11 \cdot 4} = \frac{6}{44} = \frac{3}{22}\)
Ответ: а) \(\frac{12}{5} = 2\frac{2}{5}\); б) \(\frac{5}{12}\); в) 1; г) \(\frac{39}{16} = 2 \frac{7}{16}\); д) \(\frac{3}{22}\)