25% of the cost price of an article is ₹ 600. Find its selling price when it is sold at a profit of 25%.

25% of the cost price of an article = ₹ 600

$\dfrac{1}{4}$ of the cost price of an article = ₹ 600

The cost price of an article = ₹ 600 x 4 = ₹ 2,400

Profit on the article = 25%

$\text{Profit\%} = \dfrac{\text{Profit}}{\text{C.P.}} \times 100\\[1em] \Rightarrow 25 = \dfrac{\text{Profit}}{2400} \times 100\\[1em] \Rightarrow \text{Profit} = \dfrac{25 \times 2400}{100}\\[1em] \Rightarrow \text{Profit} = \dfrac{60000}{100}\\[1em] \Rightarrow \text{Profit} = 600$

And

$\text{Gain} = \text{S.P. - C.P.}\\[1em] \Rightarrow 600 = \text{S.P.} - 2,400\\[1em] \Rightarrow \text{S.P.} = 600 + 2,400\\[1em] \Rightarrow \text{S.P.} = 3,000$

Hence, S.P. of the article = ₹ 3,000.