Ответ:

Решение:

  1. а) \( \frac{5}{9} \div \frac{10}{27} = \frac{5}{9} \times \frac{27}{10} = \frac{5 \times 27}{9 \times 10} = \frac{135}{90} = \frac{3}{2} = 1\frac{1}{2} \)
  2. б) \( \frac{7}{10} - \frac{3}{20} = \frac{7 \times 2}{10 \times 2} - \frac{3}{20} = \frac{14}{20} - \frac{3}{20} = \frac{11}{20} \)
  3. в) \( \frac{6}{25} \times \frac{5}{18} = \frac{6 \times 5}{25 \times 18} = \frac{30}{450} = \frac{1}{15} \)
  4. г) \( 5\frac{2}{7} - 2\frac{4}{21} + 3\frac{2}{3} = \frac{37}{7} - \frac{46}{21} + \frac{11}{3} = \frac{37 \times 3}{7 \times 3} - \frac{46}{21} + \frac{11 \times 7}{3 \times 7} = \frac{111}{21} - \frac{46}{21} + \frac{77}{21} = \frac{111 - 46 + 77}{21} = \frac{142}{21} = 6\frac{16}{21} \)

Ответ: а) $$1\frac{1}{2}$$; б) $$\frac{11}{20}$$; в) $$\frac{1}{15}$$; г) $$6\frac{16}{21}$$.