A lake with a constant volume of 10×106 m3 is fed by a pollution-free stream with flow rate of 50 m3/s. A factory dumps 5 m3/s of a nonconservative waste with concentration of 100 mg/L into the lake. The pollutant has a reaction rate coeeficient k of 0.25/day. Assuming is pollutant is well mixed in the lake, find the steady-state concentration of pollutant in the lake.