The value of $\frac{\left[\frac{3}{8}-\left\{\frac{3}{8}-\left(\frac{5}{8}-\frac{3}{8}\right)\right\}\right] \text { of } 4.8-0.9}{4 \frac{1}{6} \div 2.5 \times 0.2 \div \frac{1}{5} \text { of } 50+\left(\frac{3}{4}-\frac{1}{8}\right)}$ is:

$\frac{36}{79}$