In order to create a sodium-chloride solution with the lowest-possible freezing point you are instructed to mix 2.5 lb of sodium chloride with 1.00 gallon of water. Specified that 1 gallon = 3.7854 L, 1 kg = 2.205 lb, water has density 0.997 g/mL as well as freezing-point depression constant, kf of 1.86 oC kg mol-1, as well as the resulting sodium-chloride solution has a density of 1.179 g/mL, Explain what is the mass percent of sodium chloride in this solution?