866. a) 1/2-1/4; д) 3/5-13/45; б) 5/9-1/3; e) 1/3-8/27; в) 7/10-3/5; ж) 1/2-1/3; г) 16/27-1/9; з) 3/5-1/3;

a) $$ \frac{1}{2} - \frac{1}{4} = \frac{1 \cdot 2}{2 \cdot 2} - \frac{1}{4} = \frac{2}{4} - \frac{1}{4} = \frac{2-1}{4} = \frac{1}{4} $$.

Ответ: $$\frac{1}{4}$$

д) $$ \frac{3}{5} - \frac{13}{45} = \frac{3 \cdot 9}{5 \cdot 9} - \frac{13}{45} = \frac{27}{45} - \frac{13}{45} = \frac{27-13}{45} = \frac{14}{45} $$.

Ответ: $$\frac{14}{45}$$

б) $$ \frac{5}{9} - \frac{1}{3} = \frac{5}{9} - \frac{1 \cdot 3}{3 \cdot 3} = \frac{5}{9} - \frac{3}{9} = \frac{5-3}{9} = \frac{2}{9} $$.

Ответ: $$\frac{2}{9}$$

e) $$ \frac{1}{3} - \frac{8}{27} = \frac{1 \cdot 9}{3 \cdot 9} - \frac{8}{27} = \frac{9}{27} - \frac{8}{27} = \frac{9-8}{27} = \frac{1}{27} $$.

Ответ: $$\frac{1}{27}$$

в) $$ \frac{7}{10} - \frac{3}{5} = \frac{7}{10} - \frac{3 \cdot 2}{5 \cdot 2} = \frac{7}{10} - \frac{6}{10} = \frac{7-6}{10} = \frac{1}{10} $$.

Ответ: $$\frac{1}{10}$$

ж) $$ \frac{1}{2} - \frac{1}{3} = \frac{1 \cdot 3}{2 \cdot 3} - \frac{1 \cdot 2}{3 \cdot 2} = \frac{3}{6} - \frac{2}{6} = \frac{3-2}{6} = \frac{1}{6} $$.

Ответ: $$\frac{1}{6}$$

г) $$ \frac{16}{27} - \frac{1}{9} = \frac{16}{27} - \frac{1 \cdot 3}{9 \cdot 3} = \frac{16}{27} - \frac{3}{27} = \frac{16-3}{27} = \frac{13}{27} $$.

Ответ: $$\frac{13}{27}$$

з) $$ \frac{3}{5} - \frac{1}{3} = \frac{3 \cdot 3}{5 \cdot 3} - \frac{1 \cdot 5}{3 \cdot 5} = \frac{9}{15} - \frac{5}{15} = \frac{9-5}{15} = \frac{4}{15} $$.

Ответ: $$\frac{4}{15}$$