The suspended solid content of a 1-litre river water sample is 20 mg/litre. Assume that material all organic carbon and that Koc, the organic carbon-water partition coefficient for a chemical of interest, is approximately 4000 litre/kg. A laboratory filters the sample before analysis, analyzing the filtrate (water that does pass through the filter) and reporting the chemical concentration, C, of the filtrate. If the sample had not been filtered, how much of this chemical would have been measured? Express in terms of measured concentration C (mg/litre) of the filtered sample?