$(3)$ A ternary mixture containing $0\mathrm{.}4$ mole fraction of n$-$heptane $(1),0\mathrm{.}35$ n$-$octane $(2),$ and $0\mathrm{.}25$ n$-$decane $(3)$ is flashed to $P=75$kPa, and $T=125C.$ Determine:

a$.$ The equilibrium composition of the liquid $(x_i)$ and vapor $(y_i)$ formed.

b$.$ The fraction of the vapor formed.

c$.$ Repeat parts a and $b$ for $P=200$kPa and for $P=20$kPa.

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