using System;

public class Test
{
    public static void Main()
    {
        double numberOfPeople = GetNumberOfPeopleFromAverageSalary(840);

        Console.WriteLine(numberOfPeople);
    }

    public static double GetNumberOfPeopleFromAverageSalary(int average)
    {
        return (100 - average / 320) / (average / 320 - 1);
    }
}