The density of liquid Q is double that of liquid R. When the depth in liquid R is $x$, the pressure caused by the liquid is $4\,\text{kPa}$. At what depth in liquid Q does the pressure caused by the liquid become $7\,\text{kPa}$?
- A$\frac{2x}{7}$
- B$\frac{7x}{8}$
- C$\frac{8x}{7}$
- D$\frac{7x}{2}$