Water at 68 kg/min (c_{p} = 4.18 kJ/kg·K) is heated from 35 °C to 75 °C by oil in a counter-flow double-pipe exchanger; the oil enters at 110 °C and leaves at 75 °C; U = 320 W/m^{2}·°C. Calculate (a) the LMTD (answer in °C) and (b) the area (answer in m^{2}).