Three liquids are poured into a container: water that forms a $30-cm$ tall layer; oil forming a $20-cm$ tall layer; and ethyl alcohol forming a $10-cm$ tall layer. The densities of water, oil, and ethyl alcohol are $1000k\frac{g}{m^3}$;$830k\frac{g}{m^3}$; and $790k\frac{g}{m^3},$ respectively. The system is shown below.

a$.$ Determine the pressure at the bottom of the ethyl alcohol layer $(10$ pts $)$

b$.$ Determine the pressure at the bottom of the water layer $(10$ pts $)$