Question

Sanvi purchased some books for RS. 120. If she purchased 3 more books for the same amount each book would have cost her RS 20 less. Find the number of books purchased by Sanvi and the price of each book.​

Answer 1

QUESTION:-

________________________

Sanvi purchased some books for RS. 120. If she purchased 3 more books for the same amount each book would have cost her RS 20 less. Find the number of books purchased by Sanvi and the price of each book.

SOLUTION:-

________________________

• Sanvi purchased some books for RS. 120.

let the number of books purchased by sanvi be 'r'.

•the cost of each books = Rs [(120/r)]......(1)

_________________________

•she purchased 3 more books for the same amount.

•the number of books with Sanvi will be "(r+3)'.

•the cost of each books will be = Rs [120/(r+3)].....(2)

_________________________

.°. substituting the values from 1 &2.

.°. [(120/r)] - [120/(r+3)] =2

.°. 120 [(r+3-r)/r(r+3)]=2

.°. 60[3(3/(r²+3r) ]=1

.°. 60×3 = r²+3r

.°. 180=r²+3r

.°. r²+3r-180=0

.° r²+15r-12r-180=0

.°. r(r+15)-12(r+15)=0

.°. (r = 15 ) (r = -12)=0

.°. r = -15 or r =12

[Note:- neglect the minus term because books are not in minus ]

________________________

.°. the cost of each books=120/r =120/12 = Rs. 10

________________________