Выполни умножение: 1) 4/5 · 1/4; 2) 6/7 · 7/9; 3) 5/7 · 5/13; 4) 4/13 · 5/11; 5) 1/10 · 2/9; 6) 15/16 · 20/2; 7) 9/13 · 9/13; 8) 3/10 · 9/10.

1. \(\frac{4}{5}\cdot\frac{1}{4}=\frac{1}{5}\).
2. \(\frac{6}{7}\cdot\frac{7}{9}=\frac{2}{3}\).
3. \(\frac{5}{7}\cdot\frac{5}{13}=\frac{25}{91}\).
4. \(\frac{4}{13}\cdot\frac{5}{11}=\frac{20}{143}\).
5. \(\frac{1}{10}\cdot\frac{2}{9}=\frac{1}{45}\).
6. \(\frac{15}{16}\cdot\frac{20}{2}=\frac{15}{16}\cdot10=\frac{75}{8}=9\frac{3}{8}\).
7. \(\frac{9}{13}\cdot\frac{9}{13}=\frac{81}{169}\).
8. \(\frac{3}{10}\cdot\frac{9}{10}=\frac{27}{100}\).

Ответ: 1) 1/5; 2) 2/3; 3) 25/91; 4) 20/143; 5) 1/45; 6) 9 3/8; 7) 81/169; 8) 27/100.