Question

Amita buys some books for ₹1920. If she had bought 4 more books for the same amount each book would cost her ₹ 24 less. How many books did she buy? What was the initial price of one book?

Answer 1

Let the number of books purchased be x 

Therefore, the cost price of 1 book = 1920/x 

Therefore 1920/x − 1920/(x+4) = 24 

⇒ 1920 × 4 = 24x(x + 4) 

 or x² + 4x − 320 = 0 

⇒ (x + 20)(x − 16) = 0 

⇒ x = 16, x ≠ −20 

Number of books bought=16 

Price of each book =1920/16 = ₹120