B) 4 13 [ 6,5л-3-т ] - 3,2 [ n - 0,5m ]

\[\frac{4}{13} \cdot 6.5n - \frac{4}{13} \cdot 3\frac{1}{4}m - 3.2 \cdot \frac{5}{8}n + 3.2 \cdot 0.5m\]

\[3\frac{1}{4} = \frac{3 \cdot 4 + 1}{4} = \frac{13}{4}\]

\[\frac{4}{13} \cdot 6.5n = \frac{4 \cdot 6.5}{13}n = \frac{26}{13}n = 2n\]

\[\frac{4}{13} \cdot \frac{13}{4}m = \frac{4 \cdot 13}{13 \cdot 4}m = m\]

\[3.2 \cdot \frac{5}{8}n = \frac{32}{10} \cdot \frac{5}{8}n = \frac{32 \cdot 5}{10 \cdot 8}n = \frac{160}{80}n = 2n\]

\[3.2 \cdot 0.5m = 1.6m\]

\[2n - m - 2n + 1.6m\]

\[(2n - 2n) + (-m + 1.6m) = 0n + 0.6m = 0.6m\]