141. Solving a chemistry problem

When determining vanadium by the method of additions, a weighed portion of 0.5036 g of steel was transferred to the solution and its volume was brought to 50.0 ml. In two volumetric flasks of 50.0 ml, 20.0 ml aliquots of the solution were taken. A standard solution containing 0.0030 g of vanadium was added to one of these flasks, then hydrogen peroxide was added to both flasks. The solutions in flasks were brought to the mark, photometric and obtained: Ax = 0.20 and Ax a = 0.48. Calculate the percentage of vanadium in steel.