2. Solving a chemistry problem

4. A 1.2 g sample of steel was dissolved in acid and the solution was diluted with water to 50 ml. From 5 ml of this solution, after appropriate treatment, 100.00 ml of a colored solution was obtained. Its optical density was found to be 0.12. From a standard solution containing 0.1124 g H2MoO2*2H2O in 100.00 ml of solution, the following volumes were taken and after treatment with phenylhydrazine and diluted to 100.00 ml, optical densities were obtained:
Vsamples, ml 2.0 4.0 6.0 8.0 10.0
D 0.05 0.11 0.16 0.21 0.25
Calculate the mass fraction of molybdenum in steel.