Vishal and Param each sold their article at ₹1,818 but Vishal incurred a loss of 10%, while Param gained by 1%. What is the ratio of the cost price of Vishal's article to that of Param's article?

Vishal and Param each sold their article at ₹1,818 but Vishal incurred a loss of 10%.

Cost price of the article for Vishal = $$\frac{1818}{\left(100-10\right)}\times\ 100$$

= $$\frac{1818}{\left(90\right)}\times\ 100$$

= 2020

while Param gained by 1%.

Cost price of the article for Param = $$\frac{1818}{\left(100+1\right)}\times\ 100$$

= $$\frac{1818}{\left(101\right)}\times\ 100$$

= 1800

Ratio of the cost price of Vishal's article to that of Param's article = 2020 : 1800

= 101 : 90