What is the value of:
$$\dfrac{\left(1 - \dfrac{3}{4}\right) + \dfrac{1}{2}  of  \dfrac{6}{10}}{\dfrac{2}{3} \div \dfrac{4}{10} + \left(1 - \dfrac{1}{5}\right)  of  \dfrac{25}{16}}$$?

= $$\dfrac{\left(1 - \dfrac{3}{4}\right) + \dfrac{1}{2} of \dfrac{6}{10}}{\dfrac{2}{3} \div \dfrac{4}{10} + \left(1 - \dfrac{1}{5}\right) of \dfrac{25}{16}}$$

= $$\frac{\left(\frac{4}{4}-\frac{3}{4}\right)+\frac{1}{2}of\frac{3}{5}}{\frac{2}{3}\div\frac{2}{5}+\left(\frac{5}{5}-\frac{1}{5}\right)of\frac{25}{16}}$$

= $$\frac{\frac{1}{4}+\frac{3}{10}}{\frac{2}{3}\times\frac{5}{2}+\left(\frac{4}{5}\right)of\frac{25}{16}}$$

= $$\frac{\frac{5}{20}+\frac{6}{20}}{\frac{5}{3}+\frac{5}{4}}$$

= $$\frac{\frac{11}{20}}{\frac{20}{12}+\frac{15}{12}}$$

= $$\frac{\frac{11}{20}}{\frac{35}{12}}$$

= $$\frac{11}{20}\times\ \frac{12}{35}$$

= $$\frac{11}{5}\times\ \frac{3}{35}$$

= $$\frac{33}{175}$$