By selling an article, a man makes a profit of 25% of its selling price. His profit percent is = ?

According to the question,
25% of selling price
$$ = \frac{{1 \to {\text{Profit}}}}{{4 \to {\text{Selling price}}}}$$
Cost price = Selling price - Profit
Cost price = 4 - 1
Cost price = 3
$$\eqalign{ & {\text{Profit }}\% \cr & = \frac{{{\text{Profit}}}}{{{\text{Cost price}}}} \times 100 \cr & = \frac{1}{3} \times 100 \cr & = 33\frac{1}{3}\% \cr} $$