а) $$\frac{3}{7} \cdot \frac{5}{11} = \frac{3 \cdot 5}{7 \cdot 11} = \frac{15}{77}$$
Ответ: $$\frac{15}{77}$$
б) $$\frac{6}{25} \cdot \frac{5}{18} = \frac{6 \cdot 5}{25 \cdot 18} = \frac{30}{450} = \frac{1}{15}$$
Ответ: $$\frac{1}{15}$$
в) $$\frac{4}{7} \cdot 2 = \frac{4 \cdot 2}{7} = \frac{8}{7} = 1\frac{1}{7}$$
Ответ: $$1\frac{1}{7}$$
г) $$\frac{5}{9} : \frac{10}{27} = \frac{5}{9} \cdot \frac{27}{10} = \frac{5 \cdot 27}{9 \cdot 10} = \frac{135}{90} = \frac{3}{2} = 1\frac{1}{2}$$
Ответ: $$1\frac{1}{2}$$
д) $$\frac{12}{13} : 6 = \frac{12}{13} \cdot \frac{1}{6} = \frac{12 \cdot 1}{13 \cdot 6} = \frac{12}{78} = \frac{2}{13}$$
Ответ: $$\frac{2}{13}$$
e) $$4 : \frac{6}{13} = \frac{4}{1} : \frac{6}{13} = \frac{4}{1} \cdot \frac{13}{6} = \frac{4 \cdot 13}{1 \cdot 6} = \frac{52}{6} = \frac{26}{3} = 8\frac{2}{3}$$
Ответ: $$8\frac{2}{3}$$