141. Solving a chemistry problem

A weighed portion of nepheline syenite weighing m g was treated with a mixture of hydrofluoric and nitric acids and diluted to 100.0 ml.
Solid calcium nitrate was added to an aliquot of 10.00 ml, and an excess of EDTA was added at pH 3 to keep the quencher impurities in solution. Uranium was separated by extraction with a solution of tributyl phosphate in carbon tetrachloride and re-extracted from the organic phase into an aqueous solution of sodium trimetaphosphate.
To plot the calibration graph, we used aqueous solutions of uranyl nitrate containing 1.0; 3.0; 5.0; 7.0 and 9.0 μg U / ml, respectively, subjecting them to extraction and re-extraction according to the same procedure. The luminescence intensity of standard solutions turned out to be 20, 55, 90, 125, 160
Determine the mass fraction (%) of uranium in the mineral, if the luminescence intensity of the analyzed solution (1X) was:
Option 1
m. g. 2.021
Ix. 35