The sole sources of water and chloride (Cl^-) to a lake are three rivers: A, B and C. The flow rate of water in River A is 300 gpm and in River B is 550 gpm. River C flows into the lake, but the flow rate i unknown. The flow out of the latke is by River D only. The concentration of chloride in River A is 50mg/l. The chloride concentrations in River B and C are the same. The concentration of chloride in the lake is 75 mg/l. If the detention time in the lake is 2.5 years and the volume is 2400 x 10^6 gallons, find the following: a) the flow rate of River C in gpm. b) The concentration of chloride in River C in mg/l.