only the calculations please

(1) You are studying the feasibility of using a reverse osmosis membrane system to desalinate seawater (TDS = 35,000 mg/ L ) and inland brackish groundwater (TDS typically ranges from 1,000 to 10,000mg/L ). a) Estimate the ionic strength of the seawater and brackish water b) A conductivity meter provides a reading of 7,800mho/cm when placed in one of these water samples. Which water source is the sample from