45. Solving a chemistry problem

308. To analyze a mixture of Na2HPO4 and NaH2PO4 containing indifferent impurities, two samples of 600 mg each were taken. For titration of one sample in the presence of methyl orange indicator, 12.0 cm3 of 0.125 mol/dm3 of HCl solution was used, and for titration of another sample in the presence of phenolphthalein, 24.0 cm3 of 0.125 mol/dm3 of NaOH solution was used. Determine the mass fractions of sodium hydrogen phosphate and sodium dihydrogen phosphate in the mixture.