A solution that is a mixture of 0.4 mol C2H4Br2 and 0.6 mol C3H6Br2 has a vapor pressure of 145 mmHg at a particular temperature. Determine the vapor pressure of pure C3H6Br2 at this temperature, given that the vapor pressure of pure C2H4Br2 is 173 mmHg at this temperature and that the solution obeys Raoult's law.