$($a$)$ Galena and limestone having the ratio of $3$:$7($feed size $100kg)$ is treated in elutriator using $7m\frac{m}{s}$ of

water flowing upward. The size distribution of each material is shown in the table. If Stokes' law is applicable,

find the percentage of Galena and Limestone in overflow and in underflow. $($Densities of Galena and limestone

are $7500$ and $2700k\frac{g}{m^3},$ respectively$)$