Your factory discharges 500 thousand liter of wastewater daily into a river. The river flows at 10 million liters a day. It has a copper...

Your factory discharges 500 thousand liter of wastewater daily into a river. The river flows at 10 million liters a day. It has a copper concentration of 1 ppm. What is your factory's allowable maximum copper concentration in its wastewater without causing the copper concentration downstream to exceed 5 ppm?