126. Solving a chemistry problem

41. The diluted copper solution was concentrated by passing 250.0 ml of this solution through a chromatographic column containing a cation exchanger in the H + form, the column was washed with hydrochloric acid, and the solution was brought to the mark with water in a volumetric flask with a capacity of 100.0 ml. 20.00 ml of the solution was taken into a volumetric flask with a capacity of 50.0 ml, 15 ml of a 25% ammonia solution was added, brought to the mark with water and the optical density Ax=0.48 was measured at a=590 nm and I=2cm.
Under the same conditions, the optical density of a standard solution containing 2 mg of copper was measured, and 10.00 ml of the solution was placed in a 50.0 ml volumetric flask. added 15 ml of 25% ammonia solution, brought to the mark with water and measured the optical density Ast=0.56.
Determine the mass of copper in the test solution.