John was making noodles in boiling water. When he added common salt ( ) to boiling water, the water…

John was making noodles in boiling water. When he added common salt ($\text{NaCl}$) to boiling water, the water stopped boiling for a short while. If John had added $15\cdot0\text{ g}$ of $\text{NaCl}$ to $250\cdot0\text{ g}$ of water, calculate the boiling point of solution assuming that $\text{NaCl}$ dissociates completely in water. ($K_b$ for water $= 0\cdot512\text{ K kg mol}^{-1}$, molecular mass of $\text{NaCl} = 58\cdot44\text{ g mol}^{-1}$).