SSC CHSL Model Paper 12

If the cost price of a articles is the same as the selling price of b articles, then profit $\%=\frac{\mathit{a}-\mathit{b}}{\mathit{b}}\times 100$
The cost price of 20 articles is the same as the selling price of x articles.
Profit $=\frac{20-\mathit{x}}{\mathit{x}}\times 100$
$\frac{25}{100}=\frac{20-\mathit{x}}{\mathit{x}}$
Then, $80-4\mathit{x}=\mathit{x}$
Then, $\mathit{x}=\frac{80}{5}=16$ articles