A double-pipe counter-flow heat exchanger is to cool ethylene glycol (c_{p} = 2560 J/kg·°C) flowing at 3.5 kg/s from 80 °C to 40 °C by water (c_{p} = 4180 J/kg·°C) that enters at 20 °C and leaves at 55 °C. The overall heat transfer coefficient based on the inner surface area of the tube is 250 W/m^{2}·°C. Determine (a) the rate of heat transfer (kW), (b) the mass flow rate of water (kg/s) and (c) the heat transfer surface area on the inner side of the tube (m^{2}).