A trader bought two horses for Rs. 19500, he sold one at a loss 20% and the other at a profit of 15%. If the selling price of each horse is the same, then their cost prices are respectively ?

Answer: Option B

Let the CP of horse = Rs. x
Then, CP of second horse = Rs. (19500 - x)
According to the question,
$$\begin{array}{rl}& x\times \frac{80}{100}=\left(19500-x\right)\times \frac{115}{100}\\ & \Rightarrow 16x=23\left(19500-x\right)\\ & \Rightarrow 16x=448500-23x\\ & \Rightarrow 39x=448500\\ & \Rightarrow x=\frac{448500}{39}\\ & \Rightarrow x=\text{Rs}\text{.}11500\end{array}$$
∴ CP of first horse = Rs. 11500
∴ CP of second horse
= Rs. 19500 - 11500
= Rs. 8000