\[\left( \frac{4}{7} \right)^{6} \cdot \left( 1\frac{3}{4} \right)^{4} = \left( \frac{4}{7} \right)^{6} \cdot \left( \frac{7}{4} \right)^{4} = \frac{4^{6} \cdot 7^{4}}{7^{6} \cdot 4^{4}} =\]
\[= \frac{4^{2}}{7^{2}} = \frac{16}{49}\]