A $4\%$ aqueous food solution is fed at a rate of $2\mathrm{.}0$ kg s$1$ and a temperature of $70\backslash$deg C to a forward feed double$-$effect evaporator with equal surface areas. The solution is concentrated to $20\%$ by mass. The second effect is maintained at a pressure of $20$ kPa with a boiling point elevation of $8$ K$.$ Steam at $240$ kPa is available. The heat transfer coefficients in the first and second effects are $2\mathrm{.}20$ and $1\mathrm{.}50$ kW m$2$ K$1,$ respectively, and the heat capacity of each liquid stream may be assumed to be $4\mathrm{.}18$ kJ kg$1$ K$1.$ Calculate the heat transfer surface area of each effect and the steam economy. Solve by hand please.