145. Solving a chemistry problem

64. When determining manganese in an alloy by the method of comparison, a sample of an alloy weighing 0.2000 g is dissolved in a mixture of acids and transferred to a volumetric flask with a capacity of 500.00 ml. The atomic absorption of this solution at 279 nm is equal to 20.0 divisions of the scale. A standard solution of manganese with a concentration of 6.0000 μg Mn in 1.00 ml has an atomic absorption of 30.0 divisions. Determine the mass fraction of manganese in the alloy.