a dealer gets Rs.56 less if instead of selling a chair at a gain of 15%, it is sold at a gain of 8%. what is the CP of the chair?

Suppose the cost price of chair is x.
When it is sold at a gain of 8%.
Then, selling price of chair = $x+\frac{8x}{100} = \frac{108x}{100}$
When it is sold at a gain of 15%.
Then, selling price of chair = $x+\frac{15x}{100} = \frac{115x}{100}$
Now, according to the question, a dealer gets Rs.56 less if instead of selling a chair at a gain of 15%, it is sold at a gain of 8%
So we have;
$$\begin{gathered} \frac{115x}{100}-\frac{108x}{100} = 56 \\ \Rightarrow \frac{7x}{100} = 56 \\ \Rightarrow x = \frac{56\times 100}{7} = 800 \end{gathered}$$
Therefore the cost price of chair is Rs.800.