It would get colder
Explanation:
The lattice energy is the energy involved in the disruption of interactions between the ions of the salt. In this case, we have: ΔHlat = 350 kJ/mol > 0, so it is an endothermic process (the energy is absorbed).
The solvation energy is the energy involved in forming interactions between water molecules and the ions of the salt. In this case, we have: ΔHsolv = 320 kJ/mol > 0, so it is an endothermic process (the energy is absorbed).
The dissolution process involve both processes: the disruption of ion-ion interactions of the salt and the solvation process. Thus, the enthalphy change (ΔHsol) in the preparation of the solution is calculated as the addition of the lattice energy and solvation energy:
ΔHsol= ΔHlat + ΔHsolv = 350 kJ/mol + 320 kJ/mol = 370 kJ/mol
370 kJ/mol > 0 ⇒ endothermic process
Since the preparation of the solution is an endothermic process, it will absorb energy from the surroundings, so the solution would get colder.