modularity program without modifying the already written

good day I left a program to finish but I can not understand it tell me that you can not remove anything that has already been put and is modularity can someone help me?

// Complete the following program to work correctly.

public class U5Ordinario
{
    public static void main(String[] args)
    {
        int n1,n2,suma,resta,multi;
        float division;

        n1 = leerNumero("n1");
        n2 = leerNumero("n2");

        suma = suma(n1,n2);
        resta = resta(n1,n2);
        multi = multiplicacion(n1,n2);
        division = division(n1,n2);

        mostrarResultados(suma,resta,multi,division);
    }
}