The molal freezing point depression constant $K_f=4\mathrm{.}98C*kg*mo{l}^{-1}$ for a certain substance $x.$ When $6\mathrm{.}6g$ of urea $((N{H}_2{)}_{2}CO)$ are dissolved in $200.g$ of $x,$ the solution freezes at $2\mathrm{.}8C.$ Calculate the freezing point of pure $x.$

Round your answer to $2$ significant digits.