\[\frac{5^{\backslash 4\sqrt[3]{49}}}{3 - \sqrt[3]{7}} - \frac{21 + 7{\sqrt[3]{7}}^{\backslash 3 - \sqrt[3]{7}}}{4\sqrt[3]{49}} =\]
\[= \frac{20\sqrt[3]{49} - 7 \cdot \left( 3^{2} - \left( \sqrt[3]{7} \right)^{2} \right)}{4 \cdot \left( 3\sqrt[3]{49} - \sqrt[3]{343} \right)} =\]
\[= \frac{20\sqrt[3]{49} - 7 \cdot \left( 9 - \sqrt[3]{49} \right)}{4 \cdot \left( 3\sqrt[3]{49} - 7 \right)} =\]
\[= \frac{27\sqrt[3]{49} - 63}{4 \cdot \left( 3\sqrt[3]{49} - 7 \right)} =\]
\[= 2\frac{1}{4} = 2,25\]