rect answerA person sells a book for Rs.11. He gains as many percent as its cost price in rupees. What is the cost price?

The problem states that the gain percentage is equal to the cost price.

Let's denote the cost price as 'x'.

According to the problem, the selling price is Rs.11 and the gain is x% of the cost price.

So, we can write the equation as follows:

Cost Price + Gain = Selling Price

Substituting the given values into the equation, we get:

x + (x/100)*x = 11

Solving this equation will give us the cost price 'x'.

x + x^2/100 = 11

To simplify the equation, multiply all terms by 100:

100x + x^2 = 1100

Rearrange the equation to the standard quadratic form:

x^2 + 100x - 1100 = 0

This is a quadratic equation in the form of ax^2 + bx + c = 0.

Solving this equation will give us the possible values for 'x'.

The solutions of the equation are x = 10 and x = -110.

Since the cost price cannot be negative, the cost price of the book is Rs.10.