Using Raoult’s Law, we can calculate for the vapor pressure using the formula:
 P = x * P(pure)
 Where x is the mole fraction of water, P(pure) = pressure of pure water, P = pressure when in solution
 calculating for mole fraction of water:
 x = (0.42kg / 18kg/kmol) / ((0.42kg / 18kg/kmol) + (0.075kg / 192.12kg/kmol))
 x = 0.9835
 Therefore:
 P = 0.9835* P(71.93 mmHg)
 P = 70.75 mmHg