Using a mixed flow reactor$($MFR$),$ try to concentrate the selectivity from $A$ to $R$

in the following reaction.

$AR,r=k{C}_A$

$AS,r=k{C}_A^2$

Reaction rate constant $k=0\mathrm{.}25\frac{L}{\text{m}\text{o}\text{l}\text{m}\text{i}\text{n}},$ initial concentration of $A(c_{A0})=2.$

$mo\frac{l}{L},$ conversion rate of $A{x}_A=0\mathrm{.}9$

Find the concentrations of $R$ and $S(C_{R^2},C_S),$ respectively.

From the results of $1),$ what is the selectivity of $R?$

What is the yield of $R$ from the results of $2)?$