Physics Question, Please Help?

Find the Celsius temperature change of a river due to the exhausted energy from a nuclear power plant. ume that the input power to the boiler in the plant is 3.1 × 10^9 W, the efficiency of the use of this power is 15 %, and the river flow rate is 9 × 10^6kg/min. The specific heat of water is s 4186 J/kg ·◦C.