111. Solving a chemistry problem

20. When determining vanadium by the method of additions, a sample of steel was dissolved, the volume was brought to 50 ml. Then 20.0 ml aliquots of the solution were withdrawn into two 50 ml volumetric flasks. To one of them was added a sample of vanadium salt containing 0.0030 g of vanadium. Hydrogen peroxide was added to both flasks and the volumes were adjusted to the mark. Calculate the percentage of vanadium in steel if the following results were obtained from the photometry of solutions: a, r = 0.9580; Dx = 0.28; Dх st = 0.48.