Question

There r 180 multiple choice question in a test a candidate gets 4 marks for every correct answer and for every un attempt or wrongly answered question one marks is deducted from the total score of correct answer if a candidate scored 450 marks in the test his many questions did he answer correctly

Answer 1

let x = the number of questions answered correctly,
then: 180-x = the number of unattempted or wrongly answered questions.
Points earned for the x questions answered correctly = 4x
Points deducted from the 180-x unattempted or wrongly answered questions = -1(180-x).
4x - 1(180-x) = 450
4x - 180 + x = 450
5x - 180 = 450
5x = 630
x = 126
Number of questions answered correctly = 126 number of unattempted or wrongly answered questions = 180-126 = 54
Checking 4×126 = 504
for 126 questions answered correctly -1×54 = -54
for 54 unattempted or wrongly answered questions