A person bought an article and sold it at a loss of 10 percent. If he had bought it for 30 percent less price and sold it for Rs. 20 more, then he would earn a profit of 40 percent. What is the cost price of the article?

Loss on selling the article = 10%

If bought 30% less and sold for Rs. 20 more, profit = 40%

Profit = (Selling Price - Cost Price) / Cost Price × 100

Loss = (Cost Price - Selling Price) / Cost Price × 100

Solution: 

Let the CP be x .

first, selling on 10% loss,

SP = $$x \times\frac{90}{100} = 0.9x$$ 

Now, if bought it 30% less So, 

New CP = 0.7x 

Gain 40% if sold for ₹ 20 more , 

So, 

​$$0.9x + 20 = 0.7x \times \frac{140}{100} \\ \ \\ 0.9x + 20 = 0.98x \\0.08 = 20 \\ x = \frac{20}{0.08} = 250$$ 

Thus, the Cost Price = ₹250.