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?(
30 papers represents 25% of the total number of students.
Let x be the total number of students.
0.25x = 30
x = 30 / 0.25
x = 120
Ms. Quarles has 120 students in total.