On selling a pen at 5% loss and a book at 15% gain, Karim gains Rs. 7. If he sells the pen at 5% gain and the book at 10% gain, he gains Rs. 13. What is the cost price of the book in Rupees?

CAT QUANT QUESTION

On selling a pen at 5% loss and a book at 15% gain, Karim gains Rs. 7. If he sells the pen at 5% gain and the book at 10% gain, he gains Rs. 13. What is the cost price of the book in Rupees?

1. 80
2. 85
3. 95
4. 100

Answer and Explanation

Let the cost prices of a pen and a books be x and y respectively.

From 1st condition,

0.95x + 1.15y = x+y+7 … (1)

From 2nd condition,

1.05x + 1.1y = x + y +13 … (2)

Solving both (1) and (2) for y, we get y=80.