On a quiz, students were awarded a certain number of points for a correct answer and penalized a certain number of points for an incorrect answer. if a student answered all the questions on the quiz and had c correct answers, her score on the quiz was 25c – 10(15 – c). how many questions were on the quiz?

Given that the score of the student on the quiz was 25c - 10(15 - c)

It can be seen that the first term of expression for her score (i.e. 25c) shows that 25 marks were awarded to each correct answer.

The second term of the expression (i.e. 10(15 - c)) represent that 10 marks were deducted from each wrong answer.

Thus, the number of wrong answers is 15 - c.

The sum of the correct answers and the wrong answers gives the total number of questions in the quiz.

Thus, the total number of questions in the quiz is given by 15 - c + c = 15.

Therefore, there are 15 questions in the quiz.