The partial pressure of water vapour in a moist air sample of relative humidity 70% is 1.6 kPa, the total pressure being 101.325 kPa. Moist air may be treated as an ideal gas mixture of water vapour and dry air. The relation between saturation temperature (T_s in K) and saturation pressure (p_s in kPa) for water is given by ln(p_s/p_o) = 14.317 - 5304/T_s, where p_o = 101.325 kPa. The dry bulb temperature of the moist air sample (in °C) is ________.