We need to extract $(95$mol$\%)$ of A from $(A,B)$ mixture, using solvent $S.$ As shown in the below figure, two units are used. The feed to the first unit is $70mo\frac{l}{h}r$ of $($ A and $B)$ with $)=(85$mol$\%.$Pure solvent $S$ is added in the two units at rate of $40mo\frac{l}{h}r$ in each unit.

The relation between $A$ in the two phases is $n_{1A}=13\mathrm{.}5n_{2A}$ or $n_{3A}=13\mathrm{.}5n_{4A}$

Can we achieve our aim?

Final Product