the maximum concentration

hello

I just have this question need an answer asap, Thanks

You are working for the Texas Commission on Environmental Quality (TCEQ) and must issue

a discharge permit to a business. The business wishes to discharge salt into the San Antonio

River. The flow of wastewater from the business is 0.3 m3/s. The flow of water in the San Antonio River (upstream) is 0.2 m3/s. Upstream the concentration of salt in the river is 10 mg/L.What is the maximum concentration the industry can discharge if the concentration of salt in the river (after mixing) cannot exceed 100 mg/L. Include a diagram depicting the problem. The system is complete mix.