Cold water (cp = 4180 J/kg K) leading to a shower enters a thin-walled double-pipe counter-flow heat exchanger at 15 degree C at a rate of 1.25 kg/s and is heated to 60 degree C by hot water (cp = 4190 J/kg K) that enters at 100 degree C at a rate of 4 kg/s. If the overall heat transfer coefficient is 880 W/m2 K, determine the rate of heat transfer and the heat transfer surface area of the heat exchanger.