这样就对了~

public class HelloWorld{

    public static void main(String[] args) {

   int one = 10 ;

        int two = 20 ;

        int three = 0 ;

        System.out.println(three+=one+two);

        System.out.println(three+=one);

        System.out.println(three-=one);

        System.out.println(three*=one);

        System.out.println(three/=one);

        System.out.println(three%=one);