public class calculator {
    public static void main(String[] args) {
        double number = 10;
        double number1 = 15;
        double answer;
        String operator = "/";

        if (operator == "+") {
            answer = number + number1;
            System.out.println(answer);
        } else if (operator == "-") {
            answer = number - number1;
            System.out.println(answer);
        } else if (operator == "*") {
            answer = number * number1;
            System.out.println(answer);
        } else if (operator == "/") {
            answer = number / number1;
            System.out.println(answer);
        } else {
            System.out.println("the operator is wrong");
        }
    }
}