6) $$\frac{15}{4}$$($$\frac{8}{3}$$ - $$\frac{3}{16}$$m - $$\frac{5}{20}$$n) - $$\frac{3}{9}$$($$6\frac{2}{3}$$m - 4$$\frac{4}{9}$$n).

6) $$\frac{15}{4}$$($$\frac{8}{3}$$ - $$\frac{3}{16}$$m - $$\frac{5}{20}$$n) - $$\frac{3}{9}$$($$6\frac{2}{3}$$m - 4$$\frac{4}{9}$$n) = $$\frac{15}{4}$$($$\frac{8}{3}$$ - $$\frac{3}{16}$$m - $$\frac{1}{4}$$n) - $$\frac{1}{3}$$($$\frac{20}{3}$$m - $$\frac{40}{9}$$n) = $$\frac{15}{4}$$ ⋅ $$\frac{8}{3}$$ - $$\frac{15}{4}$$ ⋅ $$\frac{3}{16}$$m - $$\frac{15}{4}$$ ⋅ $$\frac{1}{4}$$n - $$\frac{1}{3}$$ ⋅ $$\frac{20}{3}$$m + $$\frac{1}{3}$$ ⋅ $$\frac{40}{9}$$n = 10 - $$\frac{45}{64}$$m - $$\frac{15}{16}$$n - $$\frac{20}{9}$$m + $$\frac{40}{27}$$n = 10 -($$\frac{45}{64}$$ + $$\frac{20}{9}$$)m + (-$$\frac{15}{16}$$ + $$\frac{40}{27}$$)n = 10 -($$\frac{405}{576}$$ + $$\frac{1280}{576}$$)m + (-$$\frac{405}{432}$$ + $$\frac{640}{432}$$)n = 10 - $$\frac{1685}{576}$$m + $$\frac{235}{432}$$n = 10 - 2$$\frac{533}{576}$$m + $$\frac{235}{432}$$n

Ответ: 10 - 2$$\frac{533}{576}$$m + $$\frac{235}{432}$$n