Water flowing at a rate of 13.85 kg/s is to be heated from 54.5 to 87.8 degree celsius in a heat exhanger by 54430 kg/h of hot gas flowing counterflow and entering at 427 degree celsius. (Cpm=1.005 kj/kg*K). The overall Uo=69.1 W/m^2*K. Calculate the exit gas temperature and the heat transfer area.