The value of $$\left( {5\frac{1}{4} \div \frac{3}{7}\,{\text{of }}\frac{1}{2}} \right) \div \left( {5\frac{1}{9} - 7\frac{7}{8} \div 9\frac{9}{{20}}} \right) \times \frac{{11}}{{21}} - \left( {5 \div 2\,{\text{of }}\frac{1}{2}} \right){\text{is:}}$$

$$\eqalign{ & \left( {5\frac{1}{4} \div \frac{3}{7}\,{\text{of }}\frac{1}{2}} \right) \div \left( {5\frac{1}{9} - 7\frac{7}{8} \div 9\frac{9}{{20}}} \right) \times \frac{{11}}{{21}} - \left( {5 \div 2\,{\text{of }}\frac{1}{2}} \right) \cr & = \left( {\frac{{21}}{4} \times \frac{{14}}{3}} \right) \div \left( {\frac{{46}}{9} - \frac{{63}}{8} \times \frac{{20}}{{189}}} \right) \times \frac{{11}}{{21}} - 5 \cr & = \frac{{49}}{2} \times \frac{{18}}{{77}} \times \frac{{11}}{{21}} - 5 \cr & = 3 - 5 \cr & = - 2 \cr} $$