here is the solution worked for me

public class Solution {
    public static void main(String[] args) {
        Apple apple = new Apple();
        Apple apple2 = new Apple();

        System.out.println("============================================================");
        System.out.println("In main method, calling apple.addPrice(50) ");
        apple.addPrice(50);
        System.out.println("\tMethod returned to main. apple.price now = " + apple.applePrice + " and apple2.applePrice = " + apple2.applePrice);
        System.out.println("============================================================");
        System.out.println("In main method, calling apple2.addPrice(100) ");
        apple2.addPrice(100);
        System.out.println("\tMethod returned to main. apple2.price now = " + apple2.applePrice + " and apple.applePrice = " + apple.applePrice);
    }

    public static class Apple {
        public static int applePrice = 0;

        public static void addPrice(int appl) {
            System.out.println("\tInside method addPrice() with argument :" + appl);
            System.out.println("\tAdding argument to current price of :" + applePrice);
            applePrice=applePrice+appl;
            System.out.println("\tapplePrice now : " + applePrice);
        }
    }
}

package com.codegym.task.task04.task0402;

/*
Price of apples

*/
public class Solution {
    public static void main(String[] args) {
        Apple apple = new Apple();
        apple.addPrice(50);
        Apple apple2 = new Apple();
        apple2.addPrice(100);
        System.out.println("The cost of apples is " + Apple.applePrice);
    }

    public static class Apple {
        public static int applePrice = 0;

        public static void addPrice(int applePrice) {
            //write your code here
            Apple.applePrice=Apple.applePrice+applePrice;
        }
    }
}