A certain substance $x$ condenses at a temperature of $115\mathrm{.}4C.$ But if a $900.g$ sample of $x$ is prepared with $76.g$ of urea $((N{H}_2{)}_{2}CO)$ dissolved in it$,$ the sample is found to have a condensation point of $116\mathrm{.}2C$ instead. Calculate the molal boiling point elevation constant $K_b$ of $x.$

Be sure your answer has the correct number of significant digits.