Naman bought few apples for Rs.720 from a shop. He negotiated the price and the shopkeeper reduced it by Rs.2 per apple. Due to this Naman could buy four more apples than what he had bought earlier. How many apples did he originally buy?

Options
a) 36
b) 44
c) 40
d) 48

Solution

Let of Apple = x
No. of apple = n
= 720

After negotiated :
Price of apple = (x – 2)
No. of apple = (n + 4)
(x – 2) (n + 4) = 720
= 720
(720 – 2x) (n + 4) = 720n
720n – 2n² – 8n + 2880 = 720n
-2n² – 8n + 2880 = 0
-n² – 8n + 1440 = 0
n² + (40 – 36)n – 1440 = 0
n² + 40n – 36n – 1440 = 0
n(n + 40) – 36(n – 40) = 0
(n – 36) (n + 40) = 0
n = 36

Ans: Number of Apples originally buy were 36