I am learning java. I am getting a lot of errors when I try to keep the methods, which I am trying to invoke, inside the main method.

I am trying to declare a couple of variables x,y. However, I want to invoke the math operations when specific methods are called, such as addMethod, subtractMethod, so on.

When I try to include the methods within the public method, I am getting an error. 

```
 package exampleclass;

public class MathLearning {
    //declaring variables
    static int x = 9;
    static int y = 2;

    public static void main(String[] args) {

        int resu=0;
        additMethod(resu);
        subtMethod(resu);
        multMethod(resu);
        divMethod(resu);    

    private static void divMethod(int resu) {
        resu = x+y;
        System.out.println(resu);

    }

    private static void multMethod(int resu) {
        resu = x-y;
        System.out.println(resu);

    }

    private static void subtMethod(int resu) {
        resu = x*y;
        System.out.println(resu);

    }

    private static void additMethod(int resu) {
        resu = x/y;
        System.out.println(resu);

    }

    }
}

```

When I keep the methods outside the main method, I do not get an error.

```
    package exampleclass;

public class MathLearning {
    //declaring variables
    static int x = 9;
    static int y = 2;

    public static void main(String[] args) {

        int resu=0;
        additMethod(resu);
        subtMethod(resu);
        multMethod(resu);
        divMethod(resu);

    }

    private static void divMethod(int resu) {
        resu = x+y;
        System.out.println(resu);

    }

    private static void multMethod(int resu) {
        resu = x-y;
        System.out.println(resu);

    }

    private static void subtMethod(int resu) {
        resu = x*y;
        System.out.println(resu);

    }

    private static void additMethod(int resu) {
        resu = x/y;
        System.out.println(resu);

    }

}

```