Question

There r 180 multiple choice questions in a test. If a candidate gets four marks of every correct answers and for every unattempted or wrong answered question one mark is detucted from the total score of correct answers. If a candidate scored 450 marks how many questions did he answer correctly

Answer 1

total score
$\\ let \: the \: number \: of \: correct \: answers \: be \: x \: \\ 4x - (180 - x) \times 1 = 4x - (180 - x) \\ it \: is \: given \: that \: the \: total \: marks \: is \: 450 \\ 4x - 180 + x = 450 \\ 5x - 180 = 450 \\ 5x = 450 + 180 \\ 5x = 630 \\ x = 630 \div 5 \\ x = 126$

Answer 2

ans. is 126 ....
let the correct ans. be x
4x-(180-x)=450
5x=630
x=126