140. Solving a chemistry problem

31. When determining vanadium by the addition method, a sample of steel with a mass of m g was dissolved in a flask with a capacity of 50 ml. Two 20.0 ml samples were placed in two 50 ml volumetric flasks. In one of them was added a weighed portion of a vanadium salt containing 0.0020 g of vanadium. Hydrogen peroxide was added to both flasks, and the volumes were brought up to the mark with water. Calculate the mass fraction in% of vanadium in steel if the following optical densities were obtained by photometry of solutions;
m AX AX + CT
0.7468 0.25 0.53