Question: User: X sells two articles for Rs. 4,000 each with No loss and No Gain in the transaction. If one was sold at a Gain of 25% then other is sold at a Loss of?
1. **Problem Statement:**
X sells two articles for $4000$ each with no overall loss or gain. One article is sold at a gain of $25\%$. We need to find the loss percentage on the other article.
2. **Understanding the problem:**
If the total transaction has no loss or gain, the total cost price equals the total selling price.
3. **Let the cost prices of the two articles be $C_1$ and $C_2$.**
Selling price of each article is $4000$.
4. **Given:**
- First article sold at $25\%$ gain.
- So, selling price $S_1 = 4000 = C_1 + 0.25 C_1 = 1.25 C_1$.
5. **Calculate $C_1$:**
$$
C_1 = \frac{4000}{1.25} = 3200
$$
6. **Total selling price:**
$$
S_1 + S_2 = 4000 + 4000 = 8000
$$
7. **Since no overall gain or loss:**
$$
C_1 + C_2 = 8000
$$
$$
3200 + C_2 = 8000
$$
$$
C_2 = 8000 - 3200 = 4800
$$
8. **Selling price of second article:**
$$
S_2 = 4000
$$
9. **Loss on second article:**
$$
\text{Loss} = C_2 - S_2 = 4800 - 4000 = 800
$$
10. **Loss percentage:**
$$
\text{Loss \%} = \frac{\text{Loss}}{C_2} \times 100 = \frac{800}{4800} \times 100
$$
11. **Simplify loss percentage:**
$$
= \frac{\cancel{800}}{6 \times \cancel{800}} \times 100 = \frac{1}{6} \times 100 = 16.67\%
$$
**Final answer:** The other article is sold at a loss of $16.67\%$.