In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you had scored 125 marks in the test.

Can you calculate how many answers given by you were wrong ?

If all the 20 questions had been answered correctly, you would have scored a total of 200 marks. Since you scored 125 marks, you have lost 75 marks.
Now, what you have to do is subtract 15 marks from 200 for every wrong answer. This is because you have to deduct 10 marks for not scoring in that question and 5 marks for answering it wrong.
15 * 5 = 75
Therefore, you answered 5 questions wrong.