Выполните действия: 1) $$90 \cdot \frac{4}{63}$$; 2) $$\frac{15}{34} \cdot 16$$; 3) $$\frac{11}{26} \cdot \frac{1}{2}$$; 4) $$\frac{1}{3} \cdot \frac{1}{5}$$; 5) $$5 \frac{5}{66} \cdot \frac{9}{20}$$; 6) $$\frac{2}{55} \cdot \frac{35}{4}$$; 7) $$2 \frac{14}{15} \cdot 5 \frac{7}{16}$$; 8) $$8 \frac{3}{4} \cdot 1 \frac{11}{15}$$;

Решим каждый пример по порядку:

1. $$90 \cdot \frac{4}{63} = \frac{90 \cdot 4}{63} = \frac{360}{63} = \frac{40}{7} = 5 \frac{5}{7}$$
2. $$\frac{15}{34} \cdot 16 = \frac{15 \cdot 16}{34} = \frac{15 \cdot 8}{17} = \frac{120}{17} = 7 \frac{1}{17}$$
3. $$\frac{11}{26} \cdot \frac{1}{2} = \frac{11 \cdot 1}{26 \cdot 2} = \frac{11}{52}$$
4. $$\frac{1}{3} \cdot \frac{1}{5} = \frac{1 \cdot 1}{3 \cdot 5} = \frac{1}{15}$$
5. $$5 \frac{5}{66} \cdot \frac{9}{20} = \frac{5 \cdot 66 + 5}{66} \cdot \frac{9}{20} = \frac{335}{66} \cdot \frac{9}{20} = \frac{335 \cdot 9}{66 \cdot 20} = \frac{335 \cdot 3}{22 \cdot 20} = \frac{1005}{440} = \frac{201}{88} = 2 \frac{25}{88}$$
6. $$\frac{2}{55} \cdot \frac{35}{4} = \frac{2 \cdot 35}{55 \cdot 4} = \frac{1 \cdot 7}{11 \cdot 2} = \frac{7}{22}$$
7. $$2 \frac{14}{15} \cdot 5 \frac{7}{16} = \frac{2 \cdot 15 + 14}{15} \cdot \frac{5 \cdot 16 + 7}{16} = \frac{44}{15} \cdot \frac{87}{16} = \frac{11 \cdot 87}{5 \cdot 4} = \frac{957}{20} = 47 \frac{17}{20}$$
8. $$8 \frac{3}{4} \cdot 1 \frac{11}{15} = \frac{8 \cdot 4 + 3}{4} \cdot \frac{1 \cdot 15 + 11}{15} = \frac{35}{4} \cdot \frac{26}{15} = \frac{7 \cdot 13}{2 \cdot 3} = \frac{91}{6} = 15 \frac{1}{6}$$

Ответ:

1. $$5 \frac{5}{7}$$
2. $$7 \frac{1}{17}$$
3. $$\frac{11}{52}$$
4. $$\frac{1}{15}$$
5. $$2 \frac{25}{88}$$
6. $$\frac{7}{22}$$
7. $$47 \frac{17}{20}$$
8. $$15 \frac{1}{6}$$