400
The problem below is asking you to:
"Mrs. Sirko wanted to make copies for every student's Thursday folder. Each class has 30 students and there are 20 classes in the school. Then she had to add in one copy for each teacher (there are 24 teachers in the school). She then counted the papers by 3's to double check that she had enough. How many times did Mrs. Sirko have to count by 3's to find out how many copies she had made?
What is multiply, add, and then divide?