82. Solving a chemistry problem

1) when determining Mn in an alloy by the comparison method, a sample of the alloy weighing 0.2 g was dissolved in a mixture of acids and transferred to a volumetric flask with a capacity of 500 cm3. The atomic absorption intensity of this solution at 279.5 nm is 20 divisions of the scale. The atomic absorption of a standard solution of Mn with a concentration of 6 μg of Mn in 1 cm3 is 30 divisions. Determine the mass fraction of Mn in the alloy.