BA LLB Banaras Hindu University 2016 Solved Paper

Let the correct answered questions $=\mathit{x}$ and and wrong answered questions $=\left(75-\mathit{x}\right)$
Total correct marks = Correct answered questions $\times 4$
Total wrong marks = Wrong answered questions $\times \left(-1\right)$
According to question,
$4\mathit{x}+\left\{\left(75-\mathit{x}\right)\times \left(-1\right)\right\}=125$
$4\mathit{x}+\left\{-75+\mathit{x}\right\}=125$
$5\mathit{x}-75=125$
$5\mathit{x}=125+75$
$5\mathit{x}=200\Rightarrow \mathit{x}=40$
Hence, student has correctly answered 40 questions and 35 questions are wrongly answered.
[Total checked numbers $=4\times 40+35\left(-1\right)=160-35$
$=125$ which is right.]