If $$\frac{4}{5}$$ of an estate be worth Rs. 16800, then the value of $$\frac{3}{7}$$ of it is -

$$\eqalign{ & \frac{4}{5}{\text{ of an estate = 16800}} \cr & {\text{1 of an estate = 16800}} \times \frac{5}{4} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 21000 \cr & \frac{3}{7}{\text{ of an estate = 21000}} \times \frac{3}{7} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 9000 \cr} $$