public class Surcharge {
  private int n;
  private double x;

  public Surcharge() {
      n = 1;
      x = 3.5;
    }

  public Surcharge(int n, double x) {
      this.n = n;
      this.x = x;
    }
  
  public int operation(int p) {
      return 10 * p + n;
    }

  public double operation(double y, int p)
    {
      return x * p + y;
    }

  public double operation(int p, double y)
    {
      return (double) n / p + y;
    }
}

class EssaiSurcharge {
  public static void main(String[] arg) {
      Surcharge surcharge;

      surcharge = new Surcharge();
      System.out.println(surcharge.operation(2));
      System.out.println(surcharge.operation(1.5, 4));
      System.out.println(surcharge.operation(4, 1.5));
      surcharge =new Surcharge(7, 2.0);
      System.out.println(surcharge.operation(2));
    }
}

/* On obtient :
21
15.5
1.75
27
*/