Calamine, which is used for the relief of skin irritations, is a mixture of zinc and iron oxides. A 1.022-g sample of dried calamine was dissolved in acid and diluted to 250.0 mL. Potassium fluoride was added to a 10.00-mL aliquot of the diluted solution to mask the iron; after suitable adjustment of the pH, Zn²⁺ consumed 38.71 mL of 0.01294 M EDTA. A second 50.00-mL aliquot was suitably buffered and titrated with 2.40 mL of 0.002727 M ZnY²⁻ solution:

 

Calculate the percentages of ZnO and Fe₂O₃ in the sample.
 

Fe3+ + ZnY2- FeY + Zn2+