Answer:
import random
class Arithmetics(object):
    trial = 2
    score = 0
    is_end = "Y"
    
    def start(self):
        while self. is_end == "Y":
            self. level1()
            self. level2()
            self. level3()
            self. is_end = input("Do you want to play again? Y/N: "). upper()
        quit()
    def level1(self):
        print("--------------------Level 1--------------------\n\n Addition:")
        for _ in iter(list, 0):
            num1 = random.randint(1,5)
            num2 = random.randint(1,5)
            if self. score == 5:
                print("Congrat! advance to next level\n")
                self. init_()
                break
            print(f"{num1} + {num2}")
            result = int(input("Your answer: "))
            if result == num1 + num2:
                self. increase_score()
            elif self. trial == 0:
                print("Sorry dear, you failed to pass the text.")
                self. end_game()
            else:
                self. trial_reduce()
    def level2(self):
        print("--------------------Level 2--------------------\n\n Addition again:")
        for _ in iter(list, 0):
            num1 = random. randint(1,9)
            num2 = random. randint(1,9)
            if self. score == 5:
                print("Congrat! advance to next level\n")
                self. init_()
                break
            print(f"{num1} + {num2}")
            result = int(input("Your answer: "))
            if result == num1 + num2:
                self. increase_score()
            elif self. trial == 0:
                print("Sorry dear, you failed to pass the text.")
                self. end_game()
            else:
                self. trial_reduce()
    def level3(self):
            print("--------------------Level 3--------------------\n\n Subtraction:")
            for _ in iter(list, 0):
                denum = random. randint(6,9)
                num = random. randint(1,5)
                if self. score == 5:
                    self. init_()
                    self. end_game()
                    break
                print(f"{denum} - {num}")
                result = int(input("Your answer: "))
                if result == denum - num:
                    self. increase_score()
                elif self. trial == 0:
                    print("Sorry dear, you failed to pass the text.")
                    self. end_game()
                else:
                    self. trial_reduce()
    #classmethod
    def trial_reduce(cls):
        cls. trial -= 1
    #classmethod
    def increase_score(cls):
        cls. score += 1
    #classmethod
    def init_(cls):
        cls. trial = 2
        cls. score = 0
    def end_game(self):
        print("Congrats kiddo! You are a math wiz.")
game = Arithmetics()
game. start()
Explanation:
The python class defines the arithmetics class with three-level mathematics for children defined as methods for the class. There are three class methods namely; 'trial_reduce', 'increase_score', and 'init_' with each of them decreasing the trial attribute, increasing the score attribute by one, and initializing the class attributes to its initial state.
The 'end_game' prints a message at the end of the program. Each level is in a loop and counts five times if the answers are correct.