Question

Ms. Quarles gave the same math unit test to all her classes. She grades 25% of the tests, which is 30 papers. How many students does Ms. Quarles have in total?

Answer 1

If Ms. Quarles graded 25% of the tests, the total number of tests is 30 / (25/100) = <<30/(25/100)=120>>120 tests.
If each test represents a student, then Ms. Quarles has 120 students. Answer: \boxed{120}.