Solving a problem in chemistry section 10 point 29

29. The alloy of lead, aluminum, copper mass was dissolved 5.44 g of a 40% solution of nitric acid. To this solution was added a solution of sulfuric acid precipitate weight was 3.03 g precipitate, and the remaining solution was passed hydrogen sulphide, while a precipitate formed that was separated and calcined in air to a constant weight. The weight of the solid residue was found to be 3.2 g Determine the mass fractions of metal in an alloy.