Question

Saanvi purchased somebooks for rupees 120 if he purchased 3 more books for the same amount each book would have caused her rupees to list find the number of books purchased by Sanvi and cost of each books​

Answer 1

The complete question is,

Saanvi purchased somebooks for rupees 120 if he purchased 3 more books for the same amount each book would have caused her 2 rupees to less find the number of books purchased by Sanvi and cost of each books​.

Given,

I]  Number of books purchased by Saanvi = x

   Amount of x books = Rs. 120

   Cost of each book = 120/x

II] Number of books purchased by Saanvi = x+3

   Amount of x books = Rs. 120

   Cost of each book = 120/(x+3)

Now, we have,

120/x - 120/(x+3) = 2

120 [ 1/x - 1/(x+3) ] = 2

1/x - 1/(x+3) = 2/120

[ (x+3) - x ] / x(x+3) = 1 / 60

60 [ (x+3) - x ]  =  x(x+3)

60 [ x + 3 - x ]  = x² + 3x

180 = x² + 3x

x² + 3x - 180 = 0

solving the above quadratic equation, we get,

x = 12 and x = -15

Considering x = 12, we have,

Number of books purchased by Saanvi = x = 12

Cost of each book = 120/x = 120/12 = 10.

Therefore, the number of books purchased by Sanvi are 12 books and the cost of each books​ is Rs. 10.