The correct answer is 55.1 k. Others have solved it in wrong way.

7.3. We have liquid ethane at I bar pressure. What is the maximum temperature the liquid ethane can be heated to before it reaches the limit of stability? Use the van der Waals equation of state (see Example 7.2) with the following data: T = 305.4 K ; P = 48.8 bar ; To = 184.5 K (at 1.013 bar) (W. Porteous and M. Blander ((1976) AICHE J., 21, p 560) report an experimental value of 269 K at the limit of stability.)