15. Find out how many questions answered correctly

Tamilselvan attended a competitive exam which contains 250 objective type questions. For each correct answer, he will get two marks, and for every wrong answer and unattempted question, one mark is deducted from a total score of correct answers. If he gets 197 marks in the test, then how many questions did Tamilselvan answer correctly?

 

The questions Tamilselvan answered correctly are .