The numerical value of the profit % is equal to the cost price of a book on selling it at Tk. 96. So, how much profit (in Tk.) is there on selling it?

Solution:

Let the CP of the book be = Tk. x
So, the profit will be x%.
SP of the book = Tk. 96

Hence,
⇒ x = {(96 - x)/x} × 100
⇒ x² + 100x - 9600 = 0
⇒ x² + 160x - 60x - 9600 = 0
⇒ x(x + 160) - 60(x + 160) = 0
⇒ x = 60, -160

So, CP of a book = Tk. 60
⇒ Profit = Tk. 96 - Tk. 60
⇒ Profit = Tk.36

Hence, the correct answer is "36".