Ответ:
1) \(\frac{2}{9} \cdot \frac{3}{8} = \frac{2 \cdot 3}{9 \cdot 8} = \frac{6}{72} = \frac{1}{12}\)
2) \(\frac{3}{7} \cdot 21 = \frac{3 \cdot 21}{7} = \frac{63}{7} = 9\)
3) \((\frac{4}{7})^2 = \frac{4}{7} \cdot \frac{4}{7} = \frac{16}{49}\)
4) \(0 \cdot \frac{3}{5} = 0\)
5) \(\frac{5}{9} : \frac{10}{27} = \frac{5}{9} \cdot \frac{27}{10} = \frac{5 \cdot 27}{9 \cdot 10} = \frac{135}{90} = \frac{3}{2} = 1\frac{1}{2}\)
6) \(20 : \frac{4}{5} = 20 \cdot \frac{5}{4} = \frac{20 \cdot 5}{4} = \frac{100}{4} = 25\)
7) \(\frac{4}{5} : 20 = \frac{4}{5} \cdot \frac{1}{20} = \frac{4 \cdot 1}{5 \cdot 20} = \frac{4}{100} = \frac{1}{25}\)
8) \(\frac{4}{5} : \frac{4}{5} = 1\)
Ответ: