A concentric tube heat exchanger having an area of 100 m2 is used to heat 5 kg/s of water that enters the heat exchanger at 50oC. The heating fluid is oil having a specific heat of 2.1 kJ/kg and a flow rate of 8 kg/s. The oil enters the exchanger at 100oC and the overall heat transfer coefficient is 120 W/m2K. Calculate the exit temperature of the oil and the heat transfer if the exchanger operates in a counterflow mode.