A student answers 75% of the questions on a math exam correctly. If she answers 15
questions correctly, how many questions are on the exam?
Let's assume there are x questions on the exam.
We know that the student answered 75% of the questions correctly, which is equal to 75/100 * x = 0.75x.
Therefore, 0.75x = 15.
Dividing both sides of the equation by 0.75, we get x = 15 / 0.75 = 20.
So, there are 20 questions on the exam.