A solution containing $3kg$ salt per $100kg$ solution is evaporated to $15\%$ in an evaporator. The heat capacity of solution is $0\mathrm{.}98$kca$\frac{l}{k}g.C$ and that of the $15\%$ solution is $0\mathrm{.}90.$ The feed temperature is $20C$ and boiling point of solution in evaporator is $104C.$ It requires $540$kcal to evaporate $1kg$ of water from the boiling solution. The steam gives up only its latent heat of vaporization, $525$kca$\frac{l}{k}g.$ Find required steam per of feed and heat transferred to feed stream.

$15$