If a bookstore owner buys 15 books less for Tk. 900 when the price of each book goes up by Tk. 3, then find the original price of a book.
ক
Tk.20
খ
Tk. 18
গ
Tk. 15
ঘ
Tk. 12
সঠিক উত্তর: Tk. 12
900⁄x- 900⁄(x+3)= 15