Help please, I don't know how to do this chemistry problem?

Question

Salt, NaCl, has a solubility of 35.7 g per 100 g of water at 0 degrees Celsius. The solubility of salt in water does not vary appreciably with temperature. NaCl is an electrolyte that is commonly used to melt ice by lowering its melting point. What is the lowest possible melting point for ice that could be obtained considering the solubility of NaCl in water? The Kf for H2O is 1.86 degrees Celsius/m

Answer 1

Moles NaCl = 35.7 g / 58.4428 g/mol =0.611

Mass water = 0.100 Kg

molality = 0.611 / 0.100 Kg = 6.11

delta T = kf x m x i

i = 2 ( NaCl >> Na+ + Cl- we get 2 ions)

delta T = 1.86 x 6.11 x 2 = 22.7 °C

freezing point = - 22.7 °C