Question

in a competitive examination one mark is awarded for each correct answer while 1/2 marks is deducted for every wrong answer.jayanti answered 120 questions and got 90 marks.how many questions did she answer correctly​

Answer 1

let k be the no of wrong answers.

then correct answers are 120-k

now (120-k)*1-k*(-1/2)=90

so k=20

so no of correct answers=100