\[- 2\frac{1}{7} \cdot ( - 3,5) = \frac{15}{17} \cdot \frac{35}{10} = \frac{15}{7} \cdot \frac{7}{2} =\]
\[= \frac{15 \cdot 7}{7 \cdot 2} = \frac{15}{2} = 7,5.\]