public class Ex13 { public static void main(String[] args){ // 클래스메서드=스태틱 메서드(객체 생성없이 사용할 수 있는 메서드) System.out.println(Calculator.add(300,200)); System.out.println(Calculator.subtract(300,200)); System.out.println(Calculator.multiple(300,200)); System.out.println(Calculator.divide(300,200)); Calculator caculator = new Calculator(); caculator.a = 300; caculator.b = 200; System.out.println(caculat..