Selling price of both articles = ₹4000 each ⇒ total SP = ₹8000
First article sold at 25% gain:
Let CP = \( x \), then
\[
x + 25% \text{ of } x = ₹4000 \Rightarrow x \times 1.25 = 4000
\Rightarrow x = ₹3200
\]
So, profit = ₹800, thus second article must be sold at a loss of ₹800 to result in no overall gain or loss.
Selling price of second article = ₹4000
Cost price = ₹4000 + ₹800 = ₹4800
Loss% = \( \frac{800}{4800} \times 100 = 16\frac{2}{3}% \)