\[ 4 \times \frac{2}{7}n + 4 \times 1 + 2\frac{1}{2} = 6 - \frac{1}{3} \times \frac{6}{7}n - \frac{1}{3} \times (-3) \]
\[ \frac{8}{7}n + 4 + \frac{5}{2} = 6 - \frac{6}{21}n + 1 \]
\[ \frac{8}{7}n + 4 + \frac{5}{2} = 6 - \frac{2}{7}n + 1 \]
\[ \frac{8}{7}n + 4 + \frac{5}{2} = 7 - \frac{2}{7}n \]
\[ \frac{8}{7}n + \frac{2}{7}n = 7 - 4 - \frac{5}{2} \]
\[ \left( \frac{8}{7} + \frac{2}{7} \right)n = 3 - \frac{5}{2} \]
\[ \frac{10}{7}n = \frac{6}{2} - \frac{5}{2} \]
\[ \frac{10}{7}n = \frac{1}{2} \]
\[ n = \frac{1}{2} \div \frac{10}{7} \]
\[ n = \frac{1}{2} \times \frac{7}{10} \]
\[ n = \frac{7}{20} \]
Ответ: 7/20