64. Solving a chemistry problem

24(1). A sample of grain weighing m g was crushed and water was added in a volume of 50.00 cm3. A solution containing 0.00300 g of calcium was added to one flask. The reagent was added to both flasks to form the absorbing compound and made up to the mark with water.
Calculate the mass fraction of Ca in the grain if the following optical densities were obtained during the photometry of the solution:
Option 1
m,g 5,000
Dx-0.230
Dx st 0.510