give the solution based on material balance

9.26 A crude salt when dissolved in water yields brine whose composition is 15% by weight of NaCl, 1% NaBr and 3% MgCl,. Some water is evaporated and 40% of salt (NaCl) crystallises in pure form. On evaporation, brine looses 70% water. For 100 kg of original brine, calculate (a) weight % of MgCl, and NaBr in the concentrate and (b) The composition of cake if all the water is evaporated