Cost of Electricity to deposit 12 grams of Magnesium is Rs 500. Cost of Electricity to deposit 18 grams of aluminium will be

12 grams of Magnesium =Rs 500 ; 12 gram of 'Mg'=GEW,  which requires one Faraday; Thus cost of  1F=Rs 500; GEW of 'Al' = 9 g; 9 g require Rs 500 18 g    require  X; X=Rs 1000