96. Solving a chemistry problem

4. A silver indicator electrode with an ideal Nernst function and a silver chloride reference electrode were immersed in 100 ml of a solution with an unknown concentration of silver ions and it was found that the potential was 0.4 V. Then exactly 1 ml of a 0.1 mol / l AgNO3 solution was added and found, that the potential of the indicator electrode became equal to 0.416 V. Determine the concentration of silver ions in the test solution.