Final answer:
To find out how many quizzes Julie takes per week, the total number of quizzes she took (20) is divided by the total number of weeks (5), which equals 4 quizzes per week.
Step-by-step explanation:
To calculate the number of quizzes Julie takes per week, we need to divide the total number of quizzes by the total number of weeks.
Over the course of 2 weeks, she took 8 quizzes, and then after vacation, she took 12 quizzes over 3 weeks. Thus, in total Julie has taken 8 + 12 = 20 quizzes over 2 + 3 = 5 weeks.
Now, to find the average number of quizzes per week, divide the total number of quizzes by the total number of weeks:
Number of quizzes per week = 20 quizzes / 5 weeks = 4 quizzes per week.