Effectiveness of Heat Exchanger

In a concentric counter flow heat exchanger, water flows through the inner tube at 25 C and leaves at 42 C. The engine oil enters at 100 C and flows in the annular flow passage. The exit temperature of the engine oil is 50 C. The mass flow rate of water and the engine oil are 1.5 kg/s and 1 kg/s, respectively. The specific heat of water and oil are 4178 J/kg.K and 2130 J/kg.K, respectively. The effectiveness of this heat exchanger is _________.