The difference between the selling price of an article at a profit of 15% and at a profit of 10% is Rs. 10. The cost price of the article is = ?

Answer: Option D

Let cost price of an article be Rs. x
According to the question,
$$\begin{array}{rl}& x+\frac{15}{100}x-\left(x+\frac{10}{100}x\right)=10\\ & \Rightarrow \frac{15x-10x}{100}=10\\ & \Rightarrow \frac{5x}{100}=10\\ & \Rightarrow 5x=1000\\ & \therefore x=200\end{array}$$
Hence. cost price of an article is Rs. 200