Quiz: always prints out 0/10 even when answers are correct [Solved]

import datetime
import random

from questions import Add, Multiply


class Quiz:
    questions = []  # list to hold questions
    answers = []  # list to hold answers

    def __init__(self):
        question_types = (Add, Multiply)  # brings in the types of questions
                                          # generate 10 random questions with numbers from 1 to 10
        for _ in range(10):  # '_' is used to tell python to throw in whatever number, 1,5,7, w/e until it reaches 10.
            num1 = random.randint(1, 10)
            num2 = random.randint(1, 10)
            question = random.choice(question_types)(num1, num2)
            self.questions.append(question)  # add these questions into self.questions

    def take_quiz(self):
        # log the start time
        self.start_time = datetime.datetime.now()

        # ask all of the questions
        for question in self.questions:  # loops through each question in the questions list
                                         # log if they got the question right
            self.answers.append(self.ask(question))
        else:
            # log end time
            self.end_time = datetime.datetime.now()

        # show a summary
        return self.summary()

    def ask(self, question):
        correct = False
        # log start time
        questions_start = datetime.datetime.now()

        # capture the answer
        answer = input(question.text + " = ")

        # check the answer
        if answer == str(question.answer):
            correct = True

        # log the end time
        questions_end = datetime.datetime.now()
        # if the answer's right, send back True
        # otherwise send back False
        # send back elapsed time too
        return correct, questions_end - questions_start

    def total_correct(self):
        # return total # of answers correct
        total = 0
        for answer in self.answers:
            if answer[0]:
                total += 1
        return total

    def summary(self):
        # print how many you got right and the total # of questions. like 5/10
        # if answer is correct:
        print("Answers correct: {}/{}".format(
                self.total_correct(), len(self.questions)
        ))
        # print total time for the question: like 30 seconds
        print("This quiz took you {} seconds total.".format(
                (self.end_time-self.start_time).seconds
        ))


Quiz().take_quiz()