FERMAT 2015 Problem 15

A music test included 50 multiple choice questions. Zoltan’s score was calculated by

  • adding 4 points for each correct answer,
  • subtracting 1 point for each incorrect answer, and
  • adding 0 points for each unanswered question.

Zoltan answered 45 of the 50 questions and his score was 135 points. The number of questions that Zoltan answered incorrectly is

Answer Choices
A. 9
B. 15
C. 41
D. 40
E. 5