Counter$-$current stage extraction was used to extract acetone from water phase into the o$-$xylene phase $($solvent$).$ The feed entering the extractor contains $7\mathrm{.}5$wt$.\%$ of acetone, the solvent entering the extractor $0\mathrm{.}5$wt$.\%$ of acetone. The mass flow rate of the solvent is $0\mathrm{.}8$kg$/$s and the mass flow rate of the feed is $1$ k$/$s$.$ the raffinate is to contain $3\mathrm{.}8$ wt$.\%$ of acetone. The extraction is carried out at $300$C$.$ Calculate the composition of the extract and the required number of the equilibrium stages