public class HelloWorld{
public static void main(String[] args) {
int one = 10 ;
int two = 20 ;
int three = 0 ;
three = one + two;
int age1=one+two;
System.out.println（"three=one+two==>"+age1）;
three += one;
int age2=three+=one;
System.out.println（"three+=one==>"+age2）;
three -= one;
int age3=three-=one;
System.out.println（"three-=one==>"+age3）;
three *= one;
int age4=three*=one;
System.out.println（"three*=one==>"+age4）;
three /= one;
int age5=three/=one;
System.out.println（"three/=one==>"+age5）;
three %= one;
int age6=three%=one;
System.out.println（"three%=one==>"+age6）;
}
}
你所有的System.out.println()中的()用的都是中文（），换成英文的()就对了。
exp{
(String[] args) {
one = ;
two = ;
three = ;
three = one + two;
age1=one+two;
System..println(+age1);
three += one;
age2=three+=one;
System..println(+age2);
three -= one;
age3=three-=one;
System..println(+age3);
three *= one;
age4=three*=one;
System..println(+age4);
three /= one;
age5=three/=one;
System..println(+age5);
three %= one;
age6=three%=one;
System..println(+age6);
}
}