98. Solving a chemistry problem

When determining iron by differential photometry, the relative optical density of a 1:1 iron sulfosalicylate complex solution measured at λ = 410 nm in a 50 mm thick cuvette is 0.29. The reference solution contains 0.0576 mg of Fe in 50.0 ml of the solution. Calculate the concentration of iron and its mass in 250 ml of the analyzed solution, if the molar absorption coefficient of the complex under these conditions is 3000 mol-1 ∙l∙cm-1.