Solve using leaching equations and draw if needed: Fresh halibut livers containing $25\mathrm{.}7$ wt $\%$ oil are to be extracted with pure ethyl ether to remove $95\%$ of the oil in a countercurrent multistage leaching process. The feed rate is $1000$ kg of fresh livers per hour. The final exit overflow solution is to contain $70$ wt $\%$ oil. The retention of solution by the inert solids $($oil$-$free liver$)$ of the liver varies as follows, where N is kg inert solid$/$kg solution retained and yA is kg oil$/$kg solution:

N yA

$4\mathrm{.}880$

$3\mathrm{.}50\mathrm{.}2$

$2\mathrm{.}470\mathrm{.}4$

$1\mathrm{.}670\mathrm{.}6$

$1\mathrm{.}390\mathrm{.}81$

Solve: $($a$)$ the amounts and composition of the exit streams.

$($b$)$ total number of theoretical stages