Question: 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? A pair of shoes is sold at a Loss of 10%, had it been sold for Rs. 9 more there would have been a Gain of 12 1/2% on it. The cost price of the article is:
1. **Problem 1:** X sells two articles for Rs. 4000 each with no loss and no gain overall. One article is sold at a gain of 25%. Find the loss percentage on the other article.
2. **Formula and rules:**
- Selling Price (SP) = Cost Price (CP) + Profit or - Loss
- Gain% = $\frac{\text{Profit}}{\text{CP}} \times 100$
- Loss% = $\frac{\text{Loss}}{\text{CP}} \times 100$
3. **Step 1:** Let the cost price of the first article be $x$.
- Since it is sold at 25% gain, its selling price is $SP_1 = x + 0.25x = 1.25x$
4. **Step 2:** Let the cost price of the second article be $y$.
- Let the loss percentage on the second article be $L$%.
- Then, $SP_2 = y - \frac{L}{100}y = y(1 - \frac{L}{100})$
5. **Step 3:** Both articles are sold for Rs. 4000 each, so:
$$1.25x = 4000 \quad \Rightarrow \quad x = \frac{4000}{1.25} = 3200$$
$$y(1 - \frac{L}{100}) = 4000$$
6. **Step 4:** Since there is no loss and no gain overall, total cost price equals total selling price:
$$x + y = SP_1 + SP_2 = 4000 + 4000 = 8000$$
Substitute $x=3200$:
$$3200 + y = 8000 \quad \Rightarrow \quad y = 4800$$
7. **Step 5:** Substitute $y=4800$ into the selling price equation:
$$4800(1 - \frac{L}{100}) = 4000$$
Divide both sides by 4800:
$$1 - \frac{L}{100} = \frac{4000}{4800} = \frac{5}{6}$$
Use cancellation notation:
$$1 - \frac{L}{100} = \frac{\cancel{4000}}{\cancel{4800}} = \frac{5}{6}$$
8. **Step 6:** Solve for $L$:
$$1 - \frac{L}{100} = \frac{5}{6} \quad \Rightarrow \quad \frac{L}{100} = 1 - \frac{5}{6} = \frac{1}{6}$$
$$L = \frac{1}{6} \times 100 = 16.67\%$$
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9. **Problem 2:** A pair of shoes is sold at a loss of 10%. If it had been sold for Rs. 9 more, there would have been a gain of 12.5% (which is $12 \frac{1}{2}\%$) on it. Find the cost price.
10. **Step 1:** Let the cost price be $C$.
- Selling price at 10% loss: $SP_1 = C - 0.10C = 0.90C$
- Selling price at 12.5% gain: $SP_2 = C + 0.125C = 1.125C$
11. **Step 2:** According to the problem:
$$SP_2 = SP_1 + 9$$
Substitute:
$$1.125C = 0.90C + 9$$
12. **Step 3:** Solve for $C$:
$$1.125C - 0.90C = 9$$
$$0.225C = 9$$
$$C = \frac{9}{0.225} = 40$$
**Final answers:**
- Loss percentage on the second article = $16.67\%$
- Cost price of the shoes = Rs. $40$