$$6 \frac{2}{3} = \frac{20}{3}$$
$$1 \frac{5}{9} = \frac{14}{9}$$
$$\frac{15}{14} - \frac{4}{7} = \frac{15}{14} - \frac{8}{14} = \frac{7}{14} = \frac{1}{2}$$
$$\frac{20}{3} \times \frac{1}{2} - \frac{14}{9} \times \frac{9}{14} = \frac{10}{3} - 1 = \frac{10}{3} - \frac{3}{3} = \frac{7}{3}$$
Ответ: $$\frac{7}{3}$$