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