A heat exchanger is to cool ethylene glycol (cp = 2.56 kJ/kg • °C) flowing at a rate of 2 kg/s from 80°C to 40°C by water (cp = 4.18 kJ/kg • °C) that enters at 20°C and leaves at 55°C. Determine (a) the rate of heat transfer and (b) the mass flow rate of water.