how do you know that you had to look on the superheated vapor table for T=100 1bar and how do you find the u for the 2.5 with out having the tempture meaning how do you know which table to use ?

A piston-cylinder assembly contains 2kg of water at 100C and I bar. The water is compressed to a saturated vapor state where the pressure is 2.5 bar. During compression, there is a heat transfer of energy from the water to its surroundings having a magnitude of 250kJ. Neglecting changes in kinetic energy and potential energy, determine the work, in kJ, for the process of the water