Rashid sells a book at a gain of 20%. If he had sold it at ₹34.51 more, he would have gained 37%. The cost price (in ₹) of the book is:

Let the cost price of the book be CP.
Initially, the book is sold at a gain of 20%, so the initial selling price is:

SP
1
​
=1.20×CP
If it had been sold for ₹34.51 more, the new selling price would be:

SP
2
​
=SP
1
​
+34.51
At this new selling price, the gain is 37%, so:

SP
2
​
=1.37×CP
Therefore, we can set up the equation:

1.37×CP−1.20×CP=34.51
0.17×CP=34.51
CP=
0.17
34.51
​

CP=
17
3451
​
=203
The cost price of the book is ₹203.