A food product is desired to be produced using $5$ stages as shown in Figure $1.$ The feeding rate of

raw material is $500k\frac{g}{?}$ hour. Many streams are marked on the diagram with their known

composition values. Current $C$ is divided into two equal currents, $E$ and $G.$ Product $P,$ with a solids

content of $80\%,$ is the desired end product. Flow K produces a by$-$product containing $25\%$ solids

at a rate of $200k\frac{g}{h}.$ Accordingly, calculate the following.

a$)$ Mass flow rate of product $P?$

b$)$ Mass flow rate of returning stream $A?$

c$)$ What is the mass flow rate of the returning stream $R?$