A mixture of iron (II) and lead (II) carbonates was calcined. As a result of this, an amount of 0.9 mol of CO2 was evolved. The mixture of metal oxides obtained by decomposing the above carbonates was treated with sulphuric acid which resulted in a mass of 151.6 g of a sulphate as precipitate. Determine the composition of the starting mixture of carbonates in mass percentage.