theoretical stages

A feed mixture containing 50 wt% n-heptane and 50 wt% methyl cyclohexane (MCH) at 298 K and 1 atm flows at a rate of 100 kg/h and is to be separated by liquid-liquid extraction into one product containing 92.5 wt% MCH and another containing 7.5 wt% MCH (both on a solvent-free basis). Aniline will be used as the solvent. Using the equilibrium data given in Table 7.8 to construct a Janacek diagram, calculate
(a) The minimum number of theoretical stages required.
(b) The minimum external extract/reflux ratio required.
(c) For an external extract/reflux ratio of 7.0, the number of theoretical stages, the position of the feed stage, and the quantities, in kg/h, of the important streams