Pomocy, co robie zle ?

public class Solution {
    public static void main(String[] args) {

        Osoba osoba = new Osoba(); // You created an objekt. Now "osoba.wiek" = 20 (see line 11!)
        System.out.println("Wiek: " + osoba.wiek);
        osoba.dostosujWiek(osoba.wiek); // You calls the method, and it sends the value 20 to the method
        System.out.println("Dostosowany wiek: " + osoba.wiek); // "osoba.wiek" was set to 60, in line 16
    }

    public static class Osoba {
        public int wiek = 20;

        public void dostosujWiek(int wiek) { // method receives the value 20. It is called hier: "wiek", local variable.
            wiek = wiek + 20; // Now "wiek" local variable is 40
            int ib = 20;
            this.wiek = wiek +ib ; // Now this.wiek is = 40+20 (=60). (Now "this.wiek" means the "wiek" variable of the "osoba" object!)
            System.out.println("Wiek w dostosujWiek() to " + wiek); // it prints 40 (See line 14!)
        }
    }
}

/* But what if the original osoba.age is not 20 but 18? Then you will send this 18 value to the method, there you name it "wiek", and you add 18 (wiek) to the age of the object (this.wiek).
That's not good.
So don't increase the "this.wiek" by "wiek"!
Rather simply by 20.
Because this was the task, increase it by 20. */